• SurrounDoku

    From Richard Heathfield@rjh@cpax.org.uk to rec.puzzles on Wed Nov 26 23:34:49 2025
    From Newsgroup: rec.puzzles

    This looks new:

    https://www.brainbashers.com/surroundokuhelp.asp

    I can't find any reference to it elseWeb, so this one might be
    Kevin's invention.


    Any strategies so far? Here are the ones I've worked out so far:

    WWW
    W0W
    WWW

    BBB
    B9B
    BBB

    |
    |BB
    |4B
    +---

    |BB
    |6B
    |BB

    |BBB
    |66B
    |BBB

    ?4?
    ?7?
    BBB

    Any more?
    --
    Richard Heathfield
    Email: rjh at cpax dot org dot uk
    "Usenet is a strange place" - dmr 29 July 1999
    Sig line 4 vacant - apply within

    --- Synchronet 3.21a-Linux NewsLink 1.2
  • From Mike Terry@news.dead.person.stones@darjeeling.plus.com to rec.puzzles on Thu Nov 27 04:14:06 2025
    From Newsgroup: rec.puzzles

    On 26/11/2025 23:34, Richard Heathfield wrote:
    This looks new:

    https://www.brainbashers.com/surroundokuhelp.asp

    I can't find any reference to it elseWeb, so this one might be Kevin's invention.

    My first thought is that they're just too easy. In fact the ones I've attempted were "trivial" in
    the sense I explain below...


    Any strategies so far? Here are the ones I've worked out so far:

    WWW
    W0W
    WWW

    ... WWW
    .0. -> WWW
    ... WWW


    BBB
    B9B
    BBB

    ... BBB
    .9. -> BBB
    ... BBB

    etc.

    |
    |BB
    |4B
    +---

    |BB
    |6B
    |BB

    |BBB
    |66B
    |BBB
    typo?

    |... |BBW
    |66. -> |BBW
    |... |BBW

    hmm, notation is inadequate - we need a way to somehow show both colour and number for individual
    squares.

    Something like

    | .. .. .. | B. B. .. | B. B. W.
    | .6 .6 .. -> | B. B6 .. -> | B. B. W.
    | .. .. .. | B. B. .. | B. B. W.

    (So this is applying two separate patterns in sequence, no need for a single meta-pattern.)

    I don't like my notation either, but don't have anything better in ASCII text.


    ?4?
    ?7?
    BBB

    .. .4 ..
    .. .7 .. -> ??? I don't see any definite squares we can fix...
    B. B. B.


    Any more?


    Some general comments:

    The overall feeling for the game is very like MineSweeper. Start from easily deduced squares, and
    then gradually work out along the edges of the known area. It's not like sudoku at all.

    There is a symmetry in the puzzle. We can swap all numbers 0-9 for 9-0 respectively, whilst also
    changing all colours black-white. [Hmm, need to modify this in the obvious way for corner and edge
    squares.]

    Eg. your pattern

    |... |BBW
    |66. -> |BBW
    |... |BBW

    has a "dual" pattern

    |... |WWB
    |03. -> |WWB
    |... |WWB

    Sometimes recognising the rules "dual" conditions might seem more natural. E.g. saying an interior
    square containing 7 must have 7 black neighbors, is exactly the same as saying it must have 2 = 9-7
    white neighbors. That could be easier to spot - e.g. if it already has 2 white neighbors, all its
    remaining neighbors must be black. (It's easier to count to 2 than 7)


    For my environment (Windows with MS Edge browser) the right-click to set a square does not work
    properly - it does set the square, but also still displays the standard (MS Edge) right-click
    context menu.

    Most serious criticism: All the above patterns can be summarised as "apply forced squares", where
    by forced squares I mean squares /directly/ implied by rules. Akin to blocking an X.X row to make
    XOX in noughts and crosses, or in Kevin's 3-In-A-Row puzzles - such patterns hardly need to be
    listed as they're just "directly forced moves". Such rules are just noting that the reader can
    correctly read the rules. All the puzzles I've attempted so far have been solvable simply from
    repeatedly applying this one simple rule which is entirely obvious from the game rules. As such,
    the puzzles seems to be uninteresting! Of course, maybe I've been unlucky in my choice of puzzles -
    I've only done a handful. I'll carry on for a few days to see if any non-trivial puzzles crop up,
    but I'll soon stop if they're all like this.

    I'm tempted to go further and suggest that if a puzzle can be solved by repeatably applying just one
    obvious rule, then arguably it's not worthy of being called a puzzle. It's on the same level with
    WordGrid "puzzles" where you have to find each of a given list of words in a grid of letters - is
    that really a puzzle? I suppose you could make such "puzzles" more fun by making them a timed
    competition - a race! (..but still not very puzzling..)

    How about this puzzle I've just invented: (I'll call the Sequidoku puzzles)

    . . . . . 30 . .

    Rules:
    1. replace each dot with a number
    2. for any two adjacent numbers, the right hand number must be one more than the left number.

    Here is one way to solve my "puzzle" :

    . . . . . 30 . .
    . . . . . 30 31 .
    . . . . 29 30 31 .
    . . . 28 29 30 31 .
    . . 27 28 29 30 31 .
    . . 27 28 29 30 31 32
    . 26 27 28 29 30 31 32
    25 26 27 28 29 30 31 32

    Solved! Again by just one obvious rule, which is actually listed in the game rules.

    NOT MUCH FUN, but no different really from Surroundoku. :(

    Kevin's "3-In-A-Row" puzzle is also in this class of "puzzles" which can all be solved with just one
    single rule. Actually, probably /two/ rules:
    1. "block /direct/ violation of game constraints (XX. --> XXO etc.)
    2. a simple but not-quite-so-obvious extension of rule 1.

    So Surroundoku is /even easier/ than 3-In-A-Row! (It's like 3-In-A-Row solvable only with rule 1!)

    It's not that Surroundoku and 3-In-A-Row are inherently uninteresting [unlike my invented
    Sequidoku!] - I'm sure someone could create genuine puzzles out of them, so I'm really making a
    criticism of Kevin's puzzle-generating process.


    Mike.

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  • From Richard Heathfield@rjh@cpax.org.uk to rec.puzzles on Thu Nov 27 16:26:05 2025
    From Newsgroup: rec.puzzles

    On 27/11/2025 04:14, Mike Terry wrote:
    On 26/11/2025 23:34, Richard Heathfield wrote:
    This looks new:

    https://www.brainbashers.com/surroundokuhelp.asp

    I can't find any reference to it elseWeb, so this one might be
    Kevin's invention.

    My first thought is that they're just too easy.-a In fact the ones
    I've attempted were "trivial" in the sense I explain below...

    The smaller ones, yes. I hit my wall at 10x10 - I suspect there's
    a knack I have yet to acquire.

    Any strategies so far? Here are the ones I've worked out so far:

    WWW
    W0W
    WWW

    ...-a-a-a WWW
    .0. -> WWW
    ...-a-a-a WWW

    Yes, but the 0W key is unaccountably missing from my keyboard.



    BBB
    B9B
    BBB

    ...-a-a-a BBB
    .9. -> BBB
    ...-a-a-a BBB

    etc.

    |
    |BB
    |4B
    +---

    |BB
    |6B
    |BB

    |BBB
    |66B
    |BBB
    typo?

    Oh yeah. I was halfway through an defence when I saw I'd typed
    that instead of...


    |...-a-a-a |BBW
    |66. -> |BBW
    |...-a-a-a |BBW

    ...that.

    I don't like my notation either, but don't have anything better
    in ASCII text.

    Quite.


    ?4?
    ?7?
    BBB

    -a..-a .4-a ..
    -a..-a .7-a ..-a ->-a ???-a I don't see any definite squares we can
    fix...
    -aB.-a B.-a B.

    a4b
    c7d
    efg

    Out of the six squares

    a4b
    c7d

    a maximum of 4 can be black, so the 7 needs to find 3 more black
    squares from somewhere else, and efg are the only candidates.

    The overall feeling for the game is very like MineSweeper.-a Start
    from easily deduced squares, and then gradually work out along
    the edges of the known area.-a It's not like sudoku at all.

    <nod>

    For my environment (Windows with MS Edge browser) the right-click
    to set a square does not work properly - it does set the square,
    but also still displays the standard (MS Edge) right-click
    context menu.

    KS may apprec a bug report?

    Most serious criticism:-a All the above patterns can be summarised
    as "apply forced squares", where by forced squares I mean
    squares /directly/ implied by rules.-a Akin to blocking an X.X row
    to make XOX in noughts and crosses, or in Kevin's 3-In-A-Row
    puzzles - such patterns hardly need to be listed as they're just
    "directly forced moves".-a Such rules are just noting that the
    reader can correctly read the rules.-a All the puzzles I've
    attempted so far have been solvable simply from repeatedly
    applying this one simple rule which is entirely obvious from the
    game rules.-a As such, the puzzles seems to be uninteresting!-a Of
    course, maybe I've been unlucky in my choice of puzzles - I've
    only done a handful.-a I'll carry on for a few days to see if any non-trivial puzzles crop up, but I'll soon stop if they're all
    like this.

    That has not been my experience, but then I'm pretty sure I'm
    quite a bit denser than the average puzzle solver.

    I'm tempted to go further and suggest that if a puzzle can be
    solved by repeatably applying just one obvious rule, then
    arguably it's not worthy of being called a puzzle.-a It's on the
    same level with WordGrid "puzzles" where you have to find each of
    a given list of words in a grid of letters - is that really a
    puzzle?-a I suppose you could make such "puzzles" more fun by
    making them a timed competition - a race! (..but still not very
    puzzling..)

    I don't like wordsearches either; when in hospital a while back
    and faced with them or nothing I did indeed try to devise
    optimising strategies.

    How about this puzzle I've just invented:-a (I'll call the
    Sequidoku puzzles)

    -a-a-a .-a .-a .-a .-a . 30-a .-a .

    Rules:
    1. replace each dot with a number
    2. for any two adjacent numbers, the right hand number must be
    one more than the left number.

    Here is one way to solve my "puzzle" :

    -a-a-a .-a .-a .-a .-a . 30-a .-a .
    -a-a-a .-a .-a .-a .-a . 30 31-a .
    -a-a-a .-a .-a .-a . 29 30 31-a .
    -a-a-a .-a .-a . 28 29 30 31-a .
    -a-a-a .-a . 27 28 29 30 31-a .
    -a-a-a .-a . 27 28 29 30 31 32
    -a-a-a . 26 27 28 29 30 31 32
    -a-a 25 26 27 28 29 30 31 32

    Solved!-a Again by just one obvious rule, which is actually listed
    in the game rules.

    NOT MUCH FUN, but no different really from Surroundoku. :(

    I have yet to discover a way to frame the one obvious rule in a
    way that gives me the solution.

    Kevin's "3-In-A-Row" puzzle is also in this class of "puzzles"
    which can all be solved with just one single rule.-a Actually,
    probably /two/ rules:
    1. "block /direct/ violation of game constraints (XX. --> XXO etc.)
    2. a simple but not-quite-so-obvious extension of rule 1.

    That's certainly true for the smaller puzzles. I have not found
    it to be a scalable fault. I find the 18x18s to be exponentially
    harder - still soluble, but by no means obvious.

    So Surroundoku is /even easier/ than 3-In-A-Row!-a (It's like 3-
    In-A-Row solvable only with rule 1!)

    Not my experience. I had several cracks at the 25x25 and gave up
    each time.

    It's not that Surroundoku and 3-In-A-Row are inherently
    uninteresting [unlike my invented Sequidoku!] - I'm sure someone
    could create genuine puzzles out of them, so I'm really making a
    criticism of Kevin's puzzle-generating process.

    Well, he's taken it down now, so perhaps we shall not see its
    like again.
    --
    Richard Heathfield
    Email: rjh at cpax dot org dot uk
    "Usenet is a strange place" - dmr 29 July 1999
    Sig line 4 vacant - apply within
    --- Synchronet 3.21a-Linux NewsLink 1.2
  • From Mike Terry@news.dead.person.stones@darjeeling.plus.com to rec.puzzles on Thu Nov 27 18:30:12 2025
    From Newsgroup: rec.puzzles

    On 27/11/2025 16:26, Richard Heathfield wrote:
    On 27/11/2025 04:14, Mike Terry wrote:
    On 26/11/2025 23:34, Richard Heathfield wrote:
    This looks new:

    https://www.brainbashers.com/surroundokuhelp.asp

    I can't find any reference to it elseWeb, so this one might be Kevin's invention.

    My first thought is that they're just too easy.a In fact the ones I've attempted were "trivial" in
    the sense I explain below...

    The smaller ones, yes. I hit my wall at 10x10 - I suspect there's a knack I have yet to acquire.

    Any strategies so far? Here are the ones I've worked out so far:

    WWW
    W0W
    WWW

    ...aaa WWW
    .0. -> WWW
    ...aaa WWW

    Yes, but the 0W key is unaccountably missing from my keyboard.



    BBB
    B9B
    BBB

    ...aaa BBB
    .9. -> BBB
    ...aaa BBB

    etc.

    |
    |BB
    |4B
    +---

    |BB
    |6B
    |BB

    |BBB
    |66B
    |BBB
    typo?

    Oh yeah. I was halfway through an defence when I saw I'd typed that instead of...


    |...aaa |BBW
    |66. -> |BBW
    |...aaa |BBW

    ...that.

    I don't like my notation either, but don't have anything better in ASCII text.

    Quite.


    ?4?
    ?7?
    BBB

    aa..a .4a ..
    aa..a .7a ..a ->a ???a I don't see any definite squares we can fix...
    aaB.a B.a B.

    a4b
    c7d
    efg

    Out of the six squares

    a4b
    c7d

    a maximum of 4 can be black, so the 7 needs to find 3 more black squares from somewhere else, and
    efg are the only candidates.

    Ah, right - that's valid. (I was misunderstanding the notation.) With my notation that would be:

    .. .4 .. .. .4 ..
    .. .7 .. -> .. .7 ..
    .. .. .. B. B. B.

    That's a genuine pattern beyond what the rules say directly! The puzzles I looked at did not
    require such advanced logic to solve...



    The overall feeling for the game is very like MineSweeper.a Start from easily deduced squares, and
    then gradually work out along the edges of the known area.a It's not like sudoku at all.

    <nod>

    For my environment (Windows with MS Edge browser) the right-click to set a square does not work
    properly - it does set the square, but also still displays the standard (MS Edge) right-click
    context menu.

    KS may apprec a bug report?

    Yeah, I'll look for a place to do that.


    Most serious criticism:a All the above patterns can be summarised as "apply forced squares", where
    by forced squares I mean squares /directly/ implied by rules.a Akin to blocking an X.X row to make
    XOX in noughts and crosses, or in Kevin's 3-In-A-Row puzzles - such patterns hardly need to be
    listed as they're just "directly forced moves".a Such rules are just noting that the reader can
    correctly read the rules.a All the puzzles I've attempted so far have been solvable simply from
    repeatedly applying this one simple rule which is entirely obvious from the game rules.a As such,
    the puzzles seems to be uninteresting!a Of course, maybe I've been unlucky in my choice of puzzles
    - I've only done a handful.a I'll carry on for a few days to see if any non-trivial puzzles crop
    up, but I'll soon stop if they're all like this.

    That has not been my experience, but then I'm pretty sure I'm quite a bit denser than the average
    puzzle solver.

    I'm tempted to go further and suggest that if a puzzle can be solved by repeatably applying just
    one obvious rule, then arguably it's not worthy of being called a puzzle.a It's on the same level
    with WordGrid "puzzles" where you have to find each of a given list of words in a grid of letters
    - is that really a puzzle?a I suppose you could make such "puzzles" more fun by making them a
    timed competition - a race! (..but still not very puzzling..)

    I don't like wordsearches either; when in hospital a while back and faced with them or nothing I did
    indeed try to devise optimising strategies.

    How about this puzzle I've just invented:a (I'll call the Sequidoku puzzles) >>
    aaaa .a .a .a .a . 30a .a .

    Rules:
    1. replace each dot with a number
    2. for any two adjacent numbers, the right hand number must be one more than the left number.

    Here is one way to solve my "puzzle" :

    aaaa .a .a .a .a . 30a .a .
    aaaa .a .a .a .a . 30 31a .
    aaaa .a .a .a . 29 30 31a .
    aaaa .a .a . 28 29 30 31a .
    aaaa .a . 27 28 29 30 31a .
    aaaa .a . 27 28 29 30 31 32
    aaaa . 26 27 28 29 30 31 32
    aaa 25 26 27 28 29 30 31 32

    Solved!a Again by just one obvious rule, which is actually listed in the game rules.

    NOT MUCH FUN, but no different really from Surroundoku. :(

    I have yet to discover a way to frame the one obvious rule in a way that gives me the solution.

    You mean for my Sequidoku puzzle? You get that when we have

    30 .

    as in the above puzzle, there's only one legal number the . can be? (31)

    We could formally make this a pattern:

    n . --> n n+1

    Similarly

    . n --> n-1 n

    Perhaps we count that as 2 patterns? Fine, but they are both just directly applying the given game
    constraints where clearly only one number is possible. Or we could make it a "procedural rule",
    something like:

    - For an empty square, if it has a filled in neighbour, then the constraints of
    Sequidoku allow only one number for the square - mark the square with that number!

    For Surroundoku the equivalent rule would be

    1. If the game constraints are directly violated, if a square is coloured anything
    but one specific colour, then you can mark the square with that colour.

    For example:

    ... WWW
    .0. -> WWW
    ... WWW

    (Making any of the W squares B would directly violate the constraint that the 0 square has 0 black
    squares as neighbors.)

    More commonly, we have more colours filled in, but the principle is the same:


    W. B. W. W. B. W.
    B. B4 W. B. B4 W.
    W. W6 .. -> W. W6 B.

    The constraints say that the middle square marked B4 has 4 black neighbors. If the bottom right
    square were marked W that would violate that constraint.

    This kind of direct reasoning has been enough for me to solve all the puzzles I tried.


    Kevin's "3-In-A-Row" puzzle is also in this class of "puzzles" which can all be solved with just
    one single rule.a Actually, probably /two/ rules:
    1. "block /direct/ violation of game constraints (XX. --> XXO etc.)
    2. a simple but not-quite-so-obvious extension of rule 1.

    That's certainly true for the smaller puzzles. I have not found it to be a scalable fault. I find
    the 18x18s to be exponentially harder - still soluble, but by no means obvious.

    I am convinced just my two "patterns" are sufficient. It's not unusual for me to "get stuck"
    solving one of the puzzles, and I mechanically go through the puzzle trying to apply the patterns,
    and conclude there are no places to apply them - I'm going to have to genuinely reason my way out of
    this, maybe coming up with a new kind of pattern! (This happens frequently in most puzzle types,
    and is what makes them fun!)

    Then eventually I see that I'd just missed something, and my two rules /were/ sufficient after all.
    Even if I've gone through the loop 4 times /really/ carefully, it will always be the case that I'm
    just missing something. I'm convinced that Kevin's puzzle generator checks that the puzzle is
    solvable by simply verifying that my two patterns are sufficient to solve the puzzle. In that
    sense, I've worked out everything there is to work out about those puzzles, and if I solved 10000
    more of them I would never have to think more than I've already thought about it. (I don't like
    that...)


    So Surroundoku is /even easier/ than 3-In-A-Row!a (It's like 3- In-A-Row solvable only with rule 1!)

    Not my experience. I had several cracks at the 25x25 and gave up each time.


    I guess the only way to check here is for you to post a position where you're stuck, and we'll see
    if there are any "direct constraint" patterns that you've missed. (Such missings wouldn't be any
    patterns you've not thought about, just blind spots which we all get. Once I did a WordSearch
    puzzle and was convinced a particular word wasn't in the grid, but then my friend looked and saw it
    straight away - Doh!

    Mike.

    --- Synchronet 3.21a-Linux NewsLink 1.2
  • From Richard Heathfield@rjh@cpax.org.uk to rec.puzzles on Thu Nov 27 20:42:45 2025
    From Newsgroup: rec.puzzles

    On 27/11/2025 18:30, Mike Terry wrote:

    242 lines - understandable, but I'm applying a liberal axe.

    On 27/11/2025 16:26, Richard Heathfield wrote:
    On 27/11/2025 04:14, Mike Terry wrote:
    On 26/11/2025 23:34, Richard Heathfield wrote:

    <snip>


    a4b
    c7d
    efg

    Out of the six squares

    a4b
    c7d

    a maximum of 4 can be black, so the 7 needs to find 3 more
    black squares from somewhere else, and efg are the only
    candidates.

    Ah, right - that's valid.-a (I was misunderstanding the
    notation.)-a With my notation that would be:

    -a ..-a .4-a ..-a-a-a-a-a ..-a .4-a ..
    -a ..-a .7-a ..-a ->-a ..-a .7-a ..
    -a ..-a ..-a ..-a-a-a-a-a B.-a B.-a B.

    Aha! Reminiscent of DOS TUI attribute bytes.

    That's a genuine pattern beyond what the rules say directly!-a The
    puzzles I looked at did not require such advanced logic to solve...

    It's tempting to cut code looking for patterns.

    The overall feeling for the game is very like MineSweeper.
    Start from easily deduced squares, and then gradually work out
    along the edges of the known area.-a It's not like sudoku at all.

    <nod>

    For my environment (Windows with MS Edge browser) the right-
    click to set a square does not work properly - it does set the
    square, but also still displays the standard (MS Edge) right-
    click context menu.

    KS may apprec a bug report?

    Yeah, I'll look for a place to do that.

    moc.srehsabniarb@emtctanoc is (I think) exactly wrong.

    How about this puzzle I've just invented:-a (I'll call the
    Sequidoku puzzles)

    <snip>

    NOT MUCH FUN, but no different really from Surroundoku. :(

    I have yet to discover a way to frame the one obvious rule in a
    way that gives me the solution.

    You mean for my Sequidoku puzzle?

    No. I meant for SurrounDoku.

    For Surroundoku the equivalent rule would be

    1.-a If the game constraints are directly violated, if a square is
    coloured anything
    -a-a-a but one specific colour, then you can mark the square with
    that colour.

    I don't see how that moves us forward.

    For example:

    -a...-a-a-a WWW
    -a.0. -> WWW
    -a...-a-a-a WWW

    (Making any of the W squares B would directly violate the
    constraint that the 0 square has 0 black squares as neighbors.)

    Sudoku's pretty shit too:

    +---+---+---+
    |953|8.6|124|
    |162|435|8.9|
    |48.|921|365|
    +---+---+---+
    |398|56.|412|
    |624|198|53.|
    |5.1|243|986|
    +---+---+---+
    |816|.54|293|
    |235|619|.48|
    |.49|382|651|
    +---+---+---+

    Just fill in the missing numbers in accordance with the rules.
    Too easy.

    More commonly, we have more colours filled in, but the principle
    is the same:


    -a W.-a B.-a W.-a-a-a-a-a W.-a B.-a W.
    -a B.-a B4-a W.-a-a-a-a-a B.-a B4-a W.
    -a W.-a W6-a ..-a ->-a W.-a W6-a B.

    The constraints say that the middle square marked B4 has 4 black neighbors.-a If the bottom right square were marked W that would
    violate that constraint.

    This kind of direct reasoning has been enough for me to solve all
    the puzzles I tried.

    It didn't work (or rather was insufficient) for me on the 25x25.

    I am convinced just my two "patterns" are sufficient.-a It's not
    unusual for me to "get stuck" solving one of the puzzles, and I
    mechanically go through the puzzle trying to apply the patterns,
    and conclude there are no places to apply them - I'm going to
    have to genuinely reason my way out of this, maybe coming up with
    a new kind of pattern!-a (This happens frequently in most puzzle
    types, and is what makes them fun!)

    That happens to me in the 3-In-A-Row.

    Then eventually I see that I'd just missed something, and my two
    rules /were/ sufficient after all. Even if I've gone through the
    loop 4 times /really/ carefully, it will always be the case that
    I'm just missing something.-a I'm convinced that Kevin's puzzle
    generator checks that the puzzle is solvable by simply verifying
    that my two patterns are sufficient to solve the puzzle.-a In that
    sense, I've worked out everything there is to work out about
    those puzzles, and if I solved 10000 more of them I would never
    have to think more than I've already thought about it.-a (I don't
    like that...)

    Fair enough, but I have yet to reach that stage.

    So Surroundoku is /even easier/ than 3-In-A-Row!-a (It's like
    3- In-A-Row solvable only with rule 1!)

    Not my experience. I had several cracks at the 25x25 and gave
    up each time.


    I guess the only way to check here is for you to post a position
    where you're stuck, and we'll see if there are any "direct
    constraint" patterns that you've missed.

    Works for me... if KS ever sees fit to restore the puzzle to his
    site. (I presume he's had some issues.)
    --
    Richard Heathfield
    Email: rjh at cpax dot org dot uk
    "Usenet is a strange place" - dmr 29 July 1999
    Sig line 4 vacant - apply within
    --- Synchronet 3.21a-Linux NewsLink 1.2
  • From HenHanna@NewsGrouper@user4055@newsgrouper.org.invalid to rec.puzzles on Fri Nov 28 00:37:32 2025
    From Newsgroup: rec.puzzles


    Mike Terry <news.dead.person.stones@darjeeling.plus.com> posted:

    On 27/11/2025 16:26, Richard Heathfield wrote:
    On 27/11/2025 04:14, Mike Terry wrote:
    On 26/11/2025 23:34, Richard Heathfield wrote:
    This looks new:

    https://www.brainbashers.com/surroundokuhelp.asp

    I can't find any reference to it elseWeb, so this one might be Kevin's invention.

    My first thought is that they're just too easy.-a In fact the ones I've attempted were "trivial" in
    the sense I explain below...

    The smaller ones, yes. I hit my wall at 10x10 - I suspect there's a knack I have yet to acquire.

    Any strategies so far? Here are the ones I've worked out so far:

    WWW
    W0W
    WWW

    ...-a-a-a WWW
    .0. -> WWW
    ...-a-a-a WWW

    Yes, but the 0W key is unaccountably missing from my keyboard.



    BBB
    B9B
    BBB

    ...-a-a-a BBB
    .9. -> BBB
    ...-a-a-a BBB

    etc.

    |
    |BB
    |4B
    +---

    |BB
    |6B
    |BB

    |BBB
    |66B
    |BBB
    typo?

    Oh yeah. I was halfway through an defence when I saw I'd typed that instead of...


    |...-a-a-a |BBW
    |66. -> |BBW
    |...-a-a-a |BBW

    ...that.

    I don't like my notation either, but don't have anything better in ASCII text.

    Quite.


    ?4?
    ?7?
    BBB

    -a-a..-a .4-a ..
    -a-a..-a .7-a ..-a ->-a ???-a I don't see any definite squares we can fix...
    -a-aB.-a B.-a B.

    a4b
    c7d
    efg

    Out of the six squares

    a4b
    c7d

    a maximum of 4 can be black, so the 7 needs to find 3 more black squares from somewhere else, and
    efg are the only candidates.

    Ah, right - that's valid. (I was misunderstanding the notation.) With my notation that would be:

    .. .4 .. .. .4 ..
    .. .7 .. -> .. .7 ..
    .. .. .. B. B. B.

    That's a genuine pattern beyond what the rules say directly! The puzzles I looked at did not
    require such advanced logic to solve...



    The overall feeling for the game is very like MineSweeper.-a Start from easily deduced squares, and
    then gradually work out along the edges of the known area.-a It's not like sudoku at all.

    <nod>

    For my environment (Windows with MS Edge browser) the right-click to set a square does not work
    properly - it does set the square, but also still displays the standard (MS Edge) right-click
    context menu.

    KS may apprec a bug report?

    Yeah, I'll look for a place to do that.


    Most serious criticism:-a All the above patterns can be summarised as "apply forced squares", where
    by forced squares I mean squares /directly/ implied by rules.-a Akin to blocking an X.X row to make
    XOX in noughts and crosses, or in Kevin's 3-In-A-Row puzzles - such patterns hardly need to be
    listed as they're just "directly forced moves".-a Such rules are just noting that the reader can
    correctly read the rules.-a All the puzzles I've attempted so far have been solvable simply from
    repeatedly applying this one simple rule which is entirely obvious from the game rules.-a As such,
    the puzzles seems to be uninteresting!-a Of course, maybe I've been unlucky in my choice of puzzles
    - I've only done a handful.-a I'll carry on for a few days to see if any non-trivial puzzles crop
    up, but I'll soon stop if they're all like this.

    That has not been my experience, but then I'm pretty sure I'm quite a bit denser than the average
    puzzle solver.

    I'm tempted to go further and suggest that if a puzzle can be solved by repeatably applying just
    one obvious rule, then arguably it's not worthy of being called a puzzle.-a It's on the same level
    with WordGrid "puzzles" where you have to find each of a given list of words in a grid of letters
    - is that really a puzzle?-a I suppose you could make such "puzzles" more fun by making them a
    timed competition - a race! (..but still not very puzzling..)

    I don't like wordsearches either; when in hospital a while back and faced with them or nothing I did
    indeed try to devise optimising strategies.

    How about this puzzle I've just invented:-a (I'll call the Sequidoku puzzles)

    -a-a-a-a .-a .-a .-a .-a . 30-a .-a .

    Rules:
    1. replace each dot with a number
    2. for any two adjacent numbers, the right hand number must be one more than the left number.

    Here is one way to solve my "puzzle" :

    -a-a-a-a .-a .-a .-a .-a . 30-a .-a .
    -a-a-a-a .-a .-a .-a .-a . 30 31-a .
    -a-a-a-a .-a .-a .-a . 29 30 31-a .
    -a-a-a-a .-a .-a . 28 29 30 31-a .
    -a-a-a-a .-a . 27 28 29 30 31-a .
    -a-a-a-a .-a . 27 28 29 30 31 32
    -a-a-a-a . 26 27 28 29 30 31 32
    -a-a-a 25 26 27 28 29 30 31 32

    Solved!-a Again by just one obvious rule, which is actually listed in the game rules.

    NOT MUCH FUN, but no different really from Surroundoku. :(

    I have yet to discover a way to frame the one obvious rule in a way that gives me the solution.

    You mean for my Sequidoku puzzle? You get that when we have

    30 .

    as in the above puzzle, there's only one legal number the . can be? (31)

    We could formally make this a pattern:

    n . --> n n+1

    Similarly

    . n --> n-1 n

    Perhaps we count that as 2 patterns? Fine, but they are both just directly applying the given game
    constraints where clearly only one number is possible. Or we could make it a "procedural rule",
    something like:

    - For an empty square, if it has a filled in neighbour, then the constraints of
    Sequidoku allow only one number for the square - mark the square with that number!

    For Surroundoku the equivalent rule would be

    1. If the game constraints are directly violated, if a square is coloured anything
    but one specific colour, then you can mark the square with that colour.

    For example:

    ... WWW
    .0. -> WWW
    ... WWW

    (Making any of the W squares B would directly violate the constraint that the 0 square has 0 black
    squares as neighbors.)

    More commonly, we have more colours filled in, but the principle is the same:


    W. B. W. W. B. W.
    B. B4 W. B. B4 W.
    W. W6 .. -> W. W6 B.

    The constraints say that the middle square marked B4 has 4 black neighbors. If the bottom right
    square were marked W that would violate that constraint.

    This kind of direct reasoning has been enough for me to solve all the puzzles I tried.


    Kevin's "3-In-A-Row" puzzle is also in this class of "puzzles" which can all be solved with just
    one single rule.-a Actually, probably /two/ rules:
    1. "block /direct/ violation of game constraints (XX. --> XXO etc.)
    2. a simple but not-quite-so-obvious extension of rule 1.

    That's certainly true for the smaller puzzles. I have not found it to be a scalable fault. I find
    the 18x18s to be exponentially harder - still soluble, but by no means obvious.

    I am convinced just my two "patterns" are sufficient. It's not unusual for me to "get stuck"
    solving one of the puzzles, and I mechanically go through the puzzle trying to apply the patterns,
    and conclude there are no places to apply them - I'm going to have to genuinely reason my way out of
    this, maybe coming up with a new kind of pattern! (This happens frequently in most puzzle types,
    and is what makes them fun!)

    Then eventually I see that I'd just missed something, and my two rules /were/ sufficient after all.
    Even if I've gone through the loop 4 times /really/ carefully, it will always be the case that I'm
    just missing something. I'm convinced that Kevin's puzzle generator checks that the puzzle is
    solvable by simply verifying that my two patterns are sufficient to solve the puzzle. In that
    sense, I've worked out everything there is to work out about those puzzles, and if I solved 10000
    more of them I would never have to think more than I've already thought about it. (I don't like
    that...)


    So Surroundoku is /even easier/ than 3-In-A-Row!-a (It's like 3- In-A-Row solvable only with rule 1!)

    Not my experience. I had several cracks at the 25x25 and gave up each time.


    I guess the only way to check here is for you to post a position where you're stuck, and we'll see
    if there are any "direct constraint" patterns that you've missed. (Such missings wouldn't be any
    patterns you've not thought about, just blind spots which we all get. Once I did a WordSearch
    puzzle and was convinced a particular word wasn't in the grid, but then my friend looked and saw it
    straight away - Doh!

    Mike.



    https://www.brainbashers.com/surroundokuhelp.asp

    The link doesn't work ... or the page was modified.


    Could someone briefly explain the rules?
    Is it like 3-In-A-Row, Tik-tak-toe, or Minimalist- GO, or Othello?



    So Surroundoku is /even easier/ than 3-In-A-Row!-a (It's like 3-In-A-Row solvable only with rule 1!)
    --- Synchronet 3.21a-Linux NewsLink 1.2
  • From Mike Terry@news.dead.person.stones@darjeeling.plus.com to rec.puzzles on Fri Nov 28 02:07:15 2025
    From Newsgroup: rec.puzzles

    On 27/11/2025 20:42, Richard Heathfield wrote:
    On 27/11/2025 18:30, Mike Terry wrote:

    242 lines - understandable, but I'm applying a liberal axe.

    On 27/11/2025 16:26, Richard Heathfield wrote:
    On 27/11/2025 04:14, Mike Terry wrote:
    On 26/11/2025 23:34, Richard Heathfield wrote:

    <snip>


    a4b
    c7d
    efg

    Out of the six squares

    a4b
    c7d

    a maximum of 4 can be black, so the 7 needs to find 3 more black squares from somewhere else, and
    efg are the only candidates.

    Ah, right - that's valid.a (I was misunderstanding the notation.)a With my notation that would be:

    aa ..a .4a ..aaaaa ..a .4a ..
    aa ..a .7a ..a ->a ..a .7a ..
    aa ..a ..a ..aaaaa B.a B.a B.

    Aha! Reminiscent of DOS TUI attribute bytes.

    That's a genuine pattern beyond what the rules say directly!a The puzzles I looked at did not
    require such advanced logic to solve...

    It's tempting to cut code looking for patterns.

    The overall feeling for the game is very like MineSweeper. Start from easily deduced squares,
    and then gradually work out along the edges of the known area.a It's not like sudoku at all.

    <nod>

    For my environment (Windows with MS Edge browser) the right- click to set a square does not work
    properly - it does set the square, but also still displays the standard (MS Edge) right- click
    context menu.

    KS may apprec a bug report?

    Yeah, I'll look for a place to do that.

    moc.srehsabniarb@emtctanoc is (I think) exactly wrong.

    How about this puzzle I've just invented:a (I'll call the Sequidoku puzzles)

    <snip>

    NOT MUCH FUN, but no different really from Surroundoku. :(

    I have yet to discover a way to frame the one obvious rule in a way that gives me the solution.

    You mean for my Sequidoku puzzle?

    No. I meant for SurrounDoku.

    For Surroundoku the equivalent rule would be

    1.a If the game constraints are directly violated, if a square is coloured anything
    aaaa but one specific colour, then you can mark the square with that colour.

    I don't see how that moves us forward.

    Well, it allows us to fill in /some/ squares, right? That's (limited) progress!


    For example:

    aa...aaa WWW
    aa.0. -> WWW
    aa...aaa WWW

    (Making any of the W squares B would directly violate the constraint that the 0 square has 0 black
    squares as neighbors.)

    Sudoku's pretty shit too:

    +---+---+---+
    |953|8.6|124|
    |162|435|8.9|
    |48.|921|365|
    +---+---+---+
    |398|56.|412|
    |624|198|53.|
    |5.1|243|986|
    +---+---+---+
    |816|.54|293|
    |235|619|.48|
    |.49|382|651|
    +---+---+---+

    You may be being facetious, but you are right /for the given puzzle/: it can be completed by
    applying one simple pattern, which is a direct application of the standard Sudoku constraints. If I
    saw that puzzle in Metro, I wouldn't even bother completing it, It's pretty shit as you say.

    The point is that the rule can (and is) used in solving /all/ sudokus, but it is not /sufficient/
    for any worthy puzzle. It may enable us to fill in a handful of squares then we're stuck - further
    reasoning and other patterns will be required. It is this variety that makes Sudoku puzzles enjoyable.

    With Suroundoku it seems to me that the equivalent rule is [might be?] /sufficient/ to solve all
    Suroundoku puzzles published on BB. You're not convinced, and now the puzzles have gone so we won't
    be able to confirm either way!

    <..snip..>

    I guess the only way to check here is for you to post a position where you're stuck, and we'll see
    if there are any "direct constraint" patterns that you've missed.

    Works for me... if KS ever sees fit to restore the puzzle to his site. (I presume he's had some
    issues.)


    Maybe lots of people said the right-click button didn't work :) Let's see if they come back...

    Mike.

    --- Synchronet 3.21a-Linux NewsLink 1.2
  • From Mike Terry@news.dead.person.stones@darjeeling.plus.com to rec.puzzles on Fri Nov 28 03:06:44 2025
    From Newsgroup: rec.puzzles

    On 28/11/2025 00:37, HenHanna@NewsGrouper wrote:

    Mike Terry <news.dead.person.stones@darjeeling.plus.com> posted:

    On 27/11/2025 16:26, Richard Heathfield wrote:
    On 27/11/2025 04:14, Mike Terry wrote:
    On 26/11/2025 23:34, Richard Heathfield wrote:
    This looks new:

    https://www.brainbashers.com/surroundokuhelp.asp

    I can't find any reference to it elseWeb, so this one might be Kevin's invention.

    My first thought is that they're just too easy.a In fact the ones I've attempted were "trivial" in
    the sense I explain below...

    The smaller ones, yes. I hit my wall at 10x10 - I suspect there's a knack I have yet to acquire.

    Any strategies so far? Here are the ones I've worked out so far:

    WWW
    W0W
    WWW

    ...aaa WWW
    .0. -> WWW
    ...aaa WWW

    Yes, but the 0W key is unaccountably missing from my keyboard.



    BBB
    B9B
    BBB

    ...aaa BBB
    .9. -> BBB
    ...aaa BBB

    etc.

    |
    |BB
    |4B
    +---

    |BB
    |6B
    |BB

    |BBB
    |66B
    |BBB
    typo?

    Oh yeah. I was halfway through an defence when I saw I'd typed that instead of...


    |...aaa |BBW
    |66. -> |BBW
    |...aaa |BBW

    ...that.

    I don't like my notation either, but don't have anything better in ASCII text.

    Quite.


    ?4?
    ?7?
    BBB

    aa..a .4a ..
    aa..a .7a ..a ->a ???a I don't see any definite squares we can fix... >>>> aaB.a B.a B.

    a4b
    c7d
    efg

    Out of the six squares

    a4b
    c7d

    a maximum of 4 can be black, so the 7 needs to find 3 more black squares from somewhere else, and
    efg are the only candidates.

    Ah, right - that's valid. (I was misunderstanding the notation.) With my notation that would be:

    .. .4 .. .. .4 ..
    .. .7 .. -> .. .7 ..
    .. .. .. B. B. B.

    That's a genuine pattern beyond what the rules say directly! The puzzles I looked at did not
    require such advanced logic to solve...



    The overall feeling for the game is very like MineSweeper.a Start from easily deduced squares, and
    then gradually work out along the edges of the known area.a It's not like sudoku at all.

    <nod>

    For my environment (Windows with MS Edge browser) the right-click to set a square does not work
    properly - it does set the square, but also still displays the standard (MS Edge) right-click
    context menu.

    KS may apprec a bug report?

    Yeah, I'll look for a place to do that.


    Most serious criticism:a All the above patterns can be summarised as "apply forced squares", where
    by forced squares I mean squares /directly/ implied by rules.a Akin to blocking an X.X row to make
    XOX in noughts and crosses, or in Kevin's 3-In-A-Row puzzles - such patterns hardly need to be
    listed as they're just "directly forced moves".a Such rules are just noting that the reader can
    correctly read the rules.a All the puzzles I've attempted so far have been solvable simply from
    repeatedly applying this one simple rule which is entirely obvious from the game rules.a As such,
    the puzzles seems to be uninteresting!a Of course, maybe I've been unlucky in my choice of puzzles
    - I've only done a handful.a I'll carry on for a few days to see if any non-trivial puzzles crop
    up, but I'll soon stop if they're all like this.

    That has not been my experience, but then I'm pretty sure I'm quite a bit denser than the average
    puzzle solver.

    I'm tempted to go further and suggest that if a puzzle can be solved by repeatably applying just
    one obvious rule, then arguably it's not worthy of being called a puzzle.a It's on the same level
    with WordGrid "puzzles" where you have to find each of a given list of words in a grid of letters
    - is that really a puzzle?a I suppose you could make such "puzzles" more fun by making them a
    timed competition - a race! (..but still not very puzzling..)

    I don't like wordsearches either; when in hospital a while back and faced with them or nothing I did
    indeed try to devise optimising strategies.

    How about this puzzle I've just invented:a (I'll call the Sequidoku puzzles)

    aaaa .a .a .a .a . 30a .a .

    Rules:
    1. replace each dot with a number
    2. for any two adjacent numbers, the right hand number must be one more than the left number.

    Here is one way to solve my "puzzle" :

    aaaa .a .a .a .a . 30a .a .
    aaaa .a .a .a .a . 30 31a .
    aaaa .a .a .a . 29 30 31a .
    aaaa .a .a . 28 29 30 31a .
    aaaa .a . 27 28 29 30 31a .
    aaaa .a . 27 28 29 30 31 32
    aaaa . 26 27 28 29 30 31 32
    aaa 25 26 27 28 29 30 31 32

    Solved!a Again by just one obvious rule, which is actually listed in the game rules.

    NOT MUCH FUN, but no different really from Surroundoku. :(

    I have yet to discover a way to frame the one obvious rule in a way that gives me the solution.

    You mean for my Sequidoku puzzle? You get that when we have

    30 .

    as in the above puzzle, there's only one legal number the . can be? (31)

    We could formally make this a pattern:

    n . --> n n+1

    Similarly

    . n --> n-1 n

    Perhaps we count that as 2 patterns? Fine, but they are both just directly applying the given game
    constraints where clearly only one number is possible. Or we could make it a "procedural rule",
    something like:

    - For an empty square, if it has a filled in neighbour, then the constraints of
    Sequidoku allow only one number for the square - mark the square with that number!

    For Surroundoku the equivalent rule would be

    1. If the game constraints are directly violated, if a square is coloured anything
    but one specific colour, then you can mark the square with that colour.

    For example:

    ... WWW
    .0. -> WWW
    ... WWW

    (Making any of the W squares B would directly violate the constraint that the 0 square has 0 black
    squares as neighbors.)

    More commonly, we have more colours filled in, but the principle is the same:


    W. B. W. W. B. W.
    B. B4 W. B. B4 W.
    W. W6 .. -> W. W6 B.

    The constraints say that the middle square marked B4 has 4 black neighbors. If the bottom right
    square were marked W that would violate that constraint.

    This kind of direct reasoning has been enough for me to solve all the puzzles I tried.


    Kevin's "3-In-A-Row" puzzle is also in this class of "puzzles" which can all be solved with just
    one single rule.a Actually, probably /two/ rules:
    1. "block /direct/ violation of game constraints (XX. --> XXO etc.)
    2. a simple but not-quite-so-obvious extension of rule 1.

    That's certainly true for the smaller puzzles. I have not found it to be a scalable fault. I find
    the 18x18s to be exponentially harder - still soluble, but by no means obvious.

    I am convinced just my two "patterns" are sufficient. It's not unusual for me to "get stuck"
    solving one of the puzzles, and I mechanically go through the puzzle trying to apply the patterns,
    and conclude there are no places to apply them - I'm going to have to genuinely reason my way out of
    this, maybe coming up with a new kind of pattern! (This happens frequently in most puzzle types,
    and is what makes them fun!)

    Then eventually I see that I'd just missed something, and my two rules /were/ sufficient after all.
    Even if I've gone through the loop 4 times /really/ carefully, it will always be the case that I'm
    just missing something. I'm convinced that Kevin's puzzle generator checks that the puzzle is
    solvable by simply verifying that my two patterns are sufficient to solve the puzzle. In that
    sense, I've worked out everything there is to work out about those puzzles, and if I solved 10000
    more of them I would never have to think more than I've already thought about it. (I don't like
    that...)


    So Surroundoku is /even easier/ than 3-In-A-Row!a (It's like 3- In-A-Row solvable only with rule 1!)

    Not my experience. I had several cracks at the 25x25 and gave up each time. >>>

    I guess the only way to check here is for you to post a position where you're stuck, and we'll see
    if there are any "direct constraint" patterns that you've missed. (Such missings wouldn't be any
    patterns you've not thought about, just blind spots which we all get. Once I did a WordSearch
    puzzle and was convinced a particular word wasn't in the grid, but then my friend looked and saw it
    straight away - Doh!

    Mike.



    https://www.brainbashers.com/surroundokuhelp.asp

    The link doesn't work ... or the page was modified.


    Could someone briefly explain the rules?
    Is it like 3-In-A-Row, Tik-tak-toe, or Minimalist- GO, or Othello?

    Kevin has removed the link. Perhaps it will come back later on.

    There is a square grid of grey squares. Some of the squares contain a number.

    The objective is to mark each square black or white, satisfying the game constraints:

    1. If a square contains a number, that number must match the number of black
    squares in the "neighbourhood" of that square.

    2. Er, that's it I think.

    For a given square, its "neighbourhood" consists of the square itself, and all the adjacent squares
    either horizontally, vertically or diagonally. (Think: king's move in chess)

    So an interior square has 9 neighbours, an edge square has 6, and a corner square has 4.

    It's not like any of the games you list. More like MineSweeper, but instead of marking squares
    safe/mine, you mark them black/white, and the constraints to follow are a bit different but in some
    ways similar to minesweeper. [I think the key feature of the constraint (1) above, is it's
    localised nature. That's in common with how MineSweeper works.]

    Here's a sample puzzle on a 4x4 grid (using dots for empty squares)

    4 . . .
    . 5 2 .
    . . 4 .
    . 3 . .

    and its solution

    B B W W
    B B W W
    B W W W
    W B B B

    (When a square with a number is coloured black/white, its number is still visible in the square)

    Mike.

    --- Synchronet 3.21a-Linux NewsLink 1.2
  • From Richard Heathfield@rjh@cpax.org.uk to rec.puzzles on Fri Nov 28 06:58:57 2025
    From Newsgroup: rec.puzzles

    On 28/11/2025 02:07, Mike Terry wrote:

    <snip>

    The point is that the rule can (and is) used in solving /all/
    sudokus, but it is not /sufficient/ for any worthy puzzle.-a It
    may enable us to fill in a handful of squares then we're stuck -
    further reasoning and other patterns will be required.-a It is
    this variety that makes Sudoku puzzles enjoyable.

    We might describe further reasoning as second order deductions,
    like my 47 adjacency leading to three free black squares. Would
    it be fair to say that a puzzle is satisfying to the Nth order,
    where N is how far you have to chase the rule down the rabbit hole?

    With Suroundoku it seems to me that the equivalent rule is [might
    be?] /sufficient/ to solve all Suroundoku puzzles published on
    BB.

    Well, it must be, because otherwise the puzzles are not soluble
    as published. But it might be that a puzzler has to apply them
    cleverly (as in X-wing, XY-wing, remote pairs etc).

    You're not convinced, and now the puzzles have gone so we
    won't be able to confirm either way!


    A waiting game, perhaps?

    I'm tempted to ask Kevin for an ETA, but in his position I
    wouldn't thank me for the nag.
    --
    Richard Heathfield
    Email: rjh at cpax dot org dot uk
    "Usenet is a strange place" - dmr 29 July 1999
    Sig line 4 vacant - apply within
    --- Synchronet 3.21a-Linux NewsLink 1.2
  • From HenHanna@NewsGrouper@user4055@newsgrouper.org.invalid to rec.puzzles on Fri Nov 28 07:50:00 2025
    From Newsgroup: rec.puzzles


    Mike Terry <news.dead.person.stones@darjeeling.plus.com> posted:

    On 28/11/2025 00:37, HenHanna@NewsGrouper wrote:

    Mike Terry <news.dead.person.stones@darjeeling.plus.com> posted:

    On 27/11/2025 16:26, Richard Heathfield wrote:
    On 27/11/2025 04:14, Mike Terry wrote:
    On 26/11/2025 23:34, Richard Heathfield wrote:
    This looks new:

    https://www.brainbashers.com/surroundokuhelp.asp

    I can't find any reference to it elseWeb, so this one might be Kevin's invention.

    My first thought is that they're just too easy.-a In fact the ones I've attempted were "trivial" in
    the sense I explain below...

    The smaller ones, yes. I hit my wall at 10x10 - I suspect there's a knack I have yet to acquire.

    Any strategies so far? Here are the ones I've worked out so far:

    WWW
    W0W
    WWW

    ...-a-a-a WWW
    .0. -> WWW
    ...-a-a-a WWW

    Yes, but the 0W key is unaccountably missing from my keyboard.



    BBB
    B9B
    BBB

    ...-a-a-a BBB
    .9. -> BBB
    ...-a-a-a BBB

    etc.

    |
    |BB
    |4B
    +---

    |BB
    |6B
    |BB

    |BBB
    |66B
    |BBB
    typo?

    Oh yeah. I was halfway through an defence when I saw I'd typed that instead of...


    |...-a-a-a |BBW
    |66. -> |BBW
    |...-a-a-a |BBW

    ...that.

    I don't like my notation either, but don't have anything better in ASCII text.

    Quite.


    ?4?
    ?7?
    BBB

    -a-a..-a .4-a ..
    -a-a..-a .7-a ..-a ->-a ???-a I don't see any definite squares we can fix...
    -a-aB.-a B.-a B.

    a4b
    c7d
    efg

    Out of the six squares

    a4b
    c7d

    a maximum of 4 can be black, so the 7 needs to find 3 more black squares from somewhere else, and
    efg are the only candidates.

    Ah, right - that's valid. (I was misunderstanding the notation.) With my notation that would be:

    .. .4 .. .. .4 ..
    .. .7 .. -> .. .7 ..
    .. .. .. B. B. B.

    That's a genuine pattern beyond what the rules say directly! The puzzles I looked at did not
    require such advanced logic to solve...



    The overall feeling for the game is very like MineSweeper.-a Start from easily deduced squares, and
    then gradually work out along the edges of the known area.-a It's not like sudoku at all.

    <nod>

    For my environment (Windows with MS Edge browser) the right-click to set a square does not work
    properly - it does set the square, but also still displays the standard (MS Edge) right-click
    context menu.

    KS may apprec a bug report?

    Yeah, I'll look for a place to do that.


    Most serious criticism:-a All the above patterns can be summarised as "apply forced squares", where
    by forced squares I mean squares /directly/ implied by rules.-a Akin to blocking an X.X row to make
    XOX in noughts and crosses, or in Kevin's 3-In-A-Row puzzles - such patterns hardly need to be
    listed as they're just "directly forced moves".-a Such rules are just noting that the reader can
    correctly read the rules.-a All the puzzles I've attempted so far have been solvable simply from
    repeatedly applying this one simple rule which is entirely obvious from the game rules.-a As such,
    the puzzles seems to be uninteresting!-a Of course, maybe I've been unlucky in my choice of puzzles
    - I've only done a handful.-a I'll carry on for a few days to see if any non-trivial puzzles crop
    up, but I'll soon stop if they're all like this.

    That has not been my experience, but then I'm pretty sure I'm quite a bit denser than the average
    puzzle solver.

    I'm tempted to go further and suggest that if a puzzle can be solved by repeatably applying just
    one obvious rule, then arguably it's not worthy of being called a puzzle.-a It's on the same level
    with WordGrid "puzzles" where you have to find each of a given list of words in a grid of letters
    - is that really a puzzle?-a I suppose you could make such "puzzles" more fun by making them a
    timed competition - a race! (..but still not very puzzling..)

    I don't like wordsearches either; when in hospital a while back and faced with them or nothing I did
    indeed try to devise optimising strategies.

    How about this puzzle I've just invented:-a (I'll call the Sequidoku puzzles)

    -a-a-a-a .-a .-a .-a .-a . 30-a .-a .

    Rules:
    1. replace each dot with a number
    2. for any two adjacent numbers, the right hand number must be one more than the left number.

    Here is one way to solve my "puzzle" :

    -a-a-a-a .-a .-a .-a .-a . 30-a .-a .
    -a-a-a-a .-a .-a .-a .-a . 30 31-a .
    -a-a-a-a .-a .-a .-a . 29 30 31-a .
    -a-a-a-a .-a .-a . 28 29 30 31-a .
    -a-a-a-a .-a . 27 28 29 30 31-a .
    -a-a-a-a .-a . 27 28 29 30 31 32
    -a-a-a-a . 26 27 28 29 30 31 32
    -a-a-a 25 26 27 28 29 30 31 32

    Solved!-a Again by just one obvious rule, which is actually listed in the game rules.

    NOT MUCH FUN, but no different really from Surroundoku. :(

    I have yet to discover a way to frame the one obvious rule in a way that gives me the solution.

    You mean for my Sequidoku puzzle? You get that when we have

    30 .

    as in the above puzzle, there's only one legal number the . can be? (31) >>
    We could formally make this a pattern:

    n . --> n n+1

    Similarly

    . n --> n-1 n

    Perhaps we count that as 2 patterns? Fine, but they are both just directly applying the given game
    constraints where clearly only one number is possible. Or we could make it a "procedural rule",
    something like:

    - For an empty square, if it has a filled in neighbour, then the constraints of
    Sequidoku allow only one number for the square - mark the square with that number!

    For Surroundoku the equivalent rule would be

    1. If the game constraints are directly violated, if a square is coloured anything
    but one specific colour, then you can mark the square with that colour.

    For example:

    ... WWW
    .0. -> WWW
    ... WWW

    (Making any of the W squares B would directly violate the constraint that the 0 square has 0 black
    squares as neighbors.)

    More commonly, we have more colours filled in, but the principle is the same:


    W. B. W. W. B. W.
    B. B4 W. B. B4 W.
    W. W6 .. -> W. W6 B.

    The constraints say that the middle square marked B4 has 4 black neighbors. If the bottom right
    square were marked W that would violate that constraint.

    This kind of direct reasoning has been enough for me to solve all the puzzles I tried.


    Kevin's "3-In-A-Row" puzzle is also in this class of "puzzles" which can all be solved with just
    one single rule.-a Actually, probably /two/ rules:
    1. "block /direct/ violation of game constraints (XX. --> XXO etc.)
    2. a simple but not-quite-so-obvious extension of rule 1.

    That's certainly true for the smaller puzzles. I have not found it to be a scalable fault. I find
    the 18x18s to be exponentially harder - still soluble, but by no means obvious.

    I am convinced just my two "patterns" are sufficient. It's not unusual for me to "get stuck"
    solving one of the puzzles, and I mechanically go through the puzzle trying to apply the patterns,
    and conclude there are no places to apply them - I'm going to have to genuinely reason my way out of
    this, maybe coming up with a new kind of pattern! (This happens frequently in most puzzle types,
    and is what makes them fun!)

    Then eventually I see that I'd just missed something, and my two rules /were/ sufficient after all.
    Even if I've gone through the loop 4 times /really/ carefully, it will always be the case that I'm
    just missing something. I'm convinced that Kevin's puzzle generator checks that the puzzle is
    solvable by simply verifying that my two patterns are sufficient to solve the puzzle. In that
    sense, I've worked out everything there is to work out about those puzzles, and if I solved 10000
    more of them I would never have to think more than I've already thought about it. (I don't like
    that...)


    So Surroundoku is /even easier/ than 3-In-A-Row!-a (It's like 3- In-A-Row solvable only with rule 1!)

    Not my experience. I had several cracks at the 25x25 and gave up each time.


    I guess the only way to check here is for you to post a position where you're stuck, and we'll see
    if there are any "direct constraint" patterns that you've missed. (Such missings wouldn't be any
    patterns you've not thought about, just blind spots which we all get. Once I did a WordSearch
    puzzle and was convinced a particular word wasn't in the grid, but then my friend looked and saw it
    straight away - Doh!

    Mike.



    https://www.brainbashers.com/surroundokuhelp.asp

    The link doesn't work ... or the page was modified.


    Could someone briefly explain the rules?
    Is it like 3-In-A-Row, Tik-tak-toe, or Minimalist- GO, or Othello?

    Kevin has removed the link. Perhaps it will come back later on.

    There is a square grid of grey squares. Some of the squares contain a number.

    The objective is to mark each square black or white, satisfying the game constraints:

    1. If a square contains a number, that number must match the number of black
    squares in the "neighbourhood" of that square.

    2. Er, that's it I think.

    For a given square, its "neighbourhood" consists of the square itself, and all the adjacent squares
    either horizontally, vertically or diagonally. (Think: king's move in chess)

    So an interior square has 9 neighbours, an edge square has 6, and a corner square has 4.

    It's not like any of the games you list. More like MineSweeper, but instead of marking squares
    safe/mine, you mark them black/white, and the constraints to follow are a bit different but in some
    ways similar to minesweeper. [I think the key feature of the constraint (1) above, is it's
    localised nature. That's in common with how MineSweeper works.]

    Here's a sample puzzle on a 4x4 grid (using dots for empty squares)

    4 . . .
    . 5 2 .
    . . 4 .
    . 3 . .

    and its solution

    B B W W
    B B W W
    B W W W
    W B B B

    (When a square with a number is coloured black/white, its number is still visible in the square)

    Mike.



    Thank you... that's somewhat like Kakkuro (kakuro).

    or more like https://en.wikipedia.org/wiki/Light_Up_(puzzle)
    --- Synchronet 3.21a-Linux NewsLink 1.2
  • From Ammammata@ammammata@tiscali.it to rec.puzzles on Fri Nov 28 11:36:15 2025
    From Newsgroup: rec.puzzles

    Richard Heathfield wrote:
    This looks new:

    https://www.brainbashers.com/surroundokuhelp.asp

    I can't find any reference to it elseWeb, so this one might be Kevin's invention.

    well, I played this Sudoku until it was available at https://www.brainbashers.com/bbtesters.asp but since yesterday
    afternoon the page changed:

    BB Testers
    There is nothing that requires testing at the moment, but thank you for looking.

    :-(
    --
    /-\ /\/\ /\/\ /-\ /\/\ /\/\ /-\ T /-\
    -=- -=- -=- -=- -=- -=- -=- -=- - -=-
    ........... [ al lavoro ] ...........
    --- Synchronet 3.21a-Linux NewsLink 1.2
  • From Mike Terry@news.dead.person.stones@darjeeling.plus.com to rec.puzzles on Fri Nov 28 18:42:14 2025
    From Newsgroup: rec.puzzles

    On 28/11/2025 06:58, Richard Heathfield wrote:
    On 28/11/2025 02:07, Mike Terry wrote:

    <snip>

    The point is that the rule can (and is) used in solving /all/ sudokus, but it is not /sufficient/
    for any worthy puzzle.a It may enable us to fill in a handful of squares then we're stuck -
    further reasoning and other patterns will be required.a It is this variety that makes Sudoku
    puzzles enjoyable.

    We might describe further reasoning as second order deductions, like my 47 adjacency leading to
    three free black squares. Would it be fair to say that a puzzle is satisfying to the Nth order,
    where N is how far you have to chase the rule down the rabbit hole?

    I don't see how to measure N, so I wouldn't word it like that, but for sure if a puzzle can be
    solved by repeatedly applying one simple rule/pattern, it's not very satisfying! The spirit behind
    your idea is ok. (Exactly what makes particular puzzles satisfying is going to be very hard to pin
    down I think!)


    With Suroundoku it seems to me that the equivalent rule is [might be?] /sufficient/ to solve all
    Suroundoku puzzles published on BB.

    Well, it must be, because otherwise the puzzles are not soluble as published. But it might be that a
    puzzler has to apply them cleverly (as in X-wing, XY-wing, remote pairs etc).

    This is just a misunderstanding of terms. "Rule" could mean one of the puzzle constraints, e.g.
    "the number in a square must match the number of black squares that are neighbours of that square",
    or a solving technique that can be applied mechanically in a given position to advance the solution"
    e.g. "if a square is such that only a single number can be assigned to it without violating a
    constraint, then mark the square with that number".

    In my prev post I meant the second meaning - a "solving rule", similar to x-wing, remote pairs etc.

    The /puzzle constraints/ are sufficient to solve any puzzle, as you say, but a particular /solving
    rule/ may or may not be sufficient. Also, such a rule might be sufficient for all puzzles published
    on a particular website, but not sufficient for all possible puzzles.


    You're not convinced, and now the puzzles have gone so we won't be able to confirm either way!


    A waiting game, perhaps?

    I'm tempted to ask Kevin for an ETA, but in his position I wouldn't thank me for the nag.

    I'd just wait and see what happens...

    Mike.

    --- Synchronet 3.21a-Linux NewsLink 1.2
  • From Mike Terry@news.dead.person.stones@darjeeling.plus.com to rec.puzzles on Fri Nov 28 18:50:38 2025
    From Newsgroup: rec.puzzles

    On 28/11/2025 07:50, HenHanna@NewsGrouper wrote:

    Mike Terry <news.dead.person.stones@darjeeling.plus.com> posted:

    On 28/11/2025 00:37, HenHanna@NewsGrouper wrote:

    Mike Terry <news.dead.person.stones@darjeeling.plus.com> posted:

    On 27/11/2025 16:26, Richard Heathfield wrote:
    On 27/11/2025 04:14, Mike Terry wrote:
    On 26/11/2025 23:34, Richard Heathfield wrote:
    This looks new:

    https://www.brainbashers.com/surroundokuhelp.asp

    I can't find any reference to it elseWeb, so this one might be Kevin's invention.

    My first thought is that they're just too easy.a In fact the ones I've attempted were "trivial" in
    the sense I explain below...

    The smaller ones, yes. I hit my wall at 10x10 - I suspect there's a knack I have yet to acquire.

    Any strategies so far? Here are the ones I've worked out so far: >>>>>>>
    WWW
    W0W
    WWW

    ...aaa WWW
    .0. -> WWW
    ...aaa WWW

    Yes, but the 0W key is unaccountably missing from my keyboard.



    BBB
    B9B
    BBB

    ...aaa BBB
    .9. -> BBB
    ...aaa BBB

    etc.

    |
    |BB
    |4B
    +---

    |BB
    |6B
    |BB

    |BBB
    |66B
    |BBB
    typo?

    Oh yeah. I was halfway through an defence when I saw I'd typed that instead of...


    |...aaa |BBW
    |66. -> |BBW
    |...aaa |BBW

    ...that.

    I don't like my notation either, but don't have anything better in ASCII text.

    Quite.


    ?4?
    ?7?
    BBB

    aa..a .4a ..
    aa..a .7a ..a ->a ???a I don't see any definite squares we can fix... >>>>>> aaB.a B.a B.

    a4b
    c7d
    efg

    Out of the six squares

    a4b
    c7d

    a maximum of 4 can be black, so the 7 needs to find 3 more black squares from somewhere else, and
    efg are the only candidates.

    Ah, right - that's valid. (I was misunderstanding the notation.) With my notation that would be:

    .. .4 .. .. .4 ..
    .. .7 .. -> .. .7 ..
    .. .. .. B. B. B.

    That's a genuine pattern beyond what the rules say directly! The puzzles I looked at did not
    require such advanced logic to solve...



    The overall feeling for the game is very like MineSweeper.a Start from easily deduced squares, and
    then gradually work out along the edges of the known area.a It's not like sudoku at all.

    <nod>

    For my environment (Windows with MS Edge browser) the right-click to set a square does not work
    properly - it does set the square, but also still displays the standard (MS Edge) right-click
    context menu.

    KS may apprec a bug report?

    Yeah, I'll look for a place to do that.


    Most serious criticism:a All the above patterns can be summarised as "apply forced squares", where
    by forced squares I mean squares /directly/ implied by rules.a Akin to blocking an X.X row to make
    XOX in noughts and crosses, or in Kevin's 3-In-A-Row puzzles - such patterns hardly need to be
    listed as they're just "directly forced moves".a Such rules are just noting that the reader can
    correctly read the rules.a All the puzzles I've attempted so far have been solvable simply from
    repeatedly applying this one simple rule which is entirely obvious from the game rules.a As such,
    the puzzles seems to be uninteresting!a Of course, maybe I've been unlucky in my choice of puzzles
    - I've only done a handful.a I'll carry on for a few days to see if any non-trivial puzzles crop
    up, but I'll soon stop if they're all like this.

    That has not been my experience, but then I'm pretty sure I'm quite a bit denser than the average
    puzzle solver.

    I'm tempted to go further and suggest that if a puzzle can be solved by repeatably applying just
    one obvious rule, then arguably it's not worthy of being called a puzzle.a It's on the same level
    with WordGrid "puzzles" where you have to find each of a given list of words in a grid of letters
    - is that really a puzzle?a I suppose you could make such "puzzles" more fun by making them a
    timed competition - a race! (..but still not very puzzling..)

    I don't like wordsearches either; when in hospital a while back and faced with them or nothing I did
    indeed try to devise optimising strategies.

    How about this puzzle I've just invented:a (I'll call the Sequidoku puzzles)

    aaaa .a .a .a .a . 30a .a .

    Rules:
    1. replace each dot with a number
    2. for any two adjacent numbers, the right hand number must be one more than the left number.

    Here is one way to solve my "puzzle" :

    aaaa .a .a .a .a . 30a .a .
    aaaa .a .a .a .a . 30 31a .
    aaaa .a .a .a . 29 30 31a .
    aaaa .a .a . 28 29 30 31a .
    aaaa .a . 27 28 29 30 31a .
    aaaa .a . 27 28 29 30 31 32
    aaaa . 26 27 28 29 30 31 32
    aaa 25 26 27 28 29 30 31 32

    Solved!a Again by just one obvious rule, which is actually listed in the game rules.

    NOT MUCH FUN, but no different really from Surroundoku. :(

    I have yet to discover a way to frame the one obvious rule in a way that gives me the solution.

    You mean for my Sequidoku puzzle? You get that when we have

    30 .

    as in the above puzzle, there's only one legal number the . can be? (31) >>>>
    We could formally make this a pattern:

    n . --> n n+1

    Similarly

    . n --> n-1 n

    Perhaps we count that as 2 patterns? Fine, but they are both just directly applying the given game
    constraints where clearly only one number is possible. Or we could make it a "procedural rule",
    something like:

    - For an empty square, if it has a filled in neighbour, then the constraints of
    Sequidoku allow only one number for the square - mark the square with that number!

    For Surroundoku the equivalent rule would be

    1. If the game constraints are directly violated, if a square is coloured anything
    but one specific colour, then you can mark the square with that colour.

    For example:

    ... WWW
    .0. -> WWW
    ... WWW

    (Making any of the W squares B would directly violate the constraint that the 0 square has 0 black
    squares as neighbors.)

    More commonly, we have more colours filled in, but the principle is the same:


    W. B. W. W. B. W.
    B. B4 W. B. B4 W.
    W. W6 .. -> W. W6 B.

    The constraints say that the middle square marked B4 has 4 black neighbors. If the bottom right
    square were marked W that would violate that constraint.

    This kind of direct reasoning has been enough for me to solve all the puzzles I tried.


    Kevin's "3-In-A-Row" puzzle is also in this class of "puzzles" which can all be solved with just
    one single rule.a Actually, probably /two/ rules:
    1. "block /direct/ violation of game constraints (XX. --> XXO etc.) >>>>>> 2. a simple but not-quite-so-obvious extension of rule 1.

    That's certainly true for the smaller puzzles. I have not found it to be a scalable fault. I find
    the 18x18s to be exponentially harder - still soluble, but by no means obvious.

    I am convinced just my two "patterns" are sufficient. It's not unusual for me to "get stuck"
    solving one of the puzzles, and I mechanically go through the puzzle trying to apply the patterns,
    and conclude there are no places to apply them - I'm going to have to genuinely reason my way out of
    this, maybe coming up with a new kind of pattern! (This happens frequently in most puzzle types,
    and is what makes them fun!)

    Then eventually I see that I'd just missed something, and my two rules /were/ sufficient after all.
    Even if I've gone through the loop 4 times /really/ carefully, it will always be the case that I'm
    just missing something. I'm convinced that Kevin's puzzle generator checks that the puzzle is
    solvable by simply verifying that my two patterns are sufficient to solve the puzzle. In that
    sense, I've worked out everything there is to work out about those puzzles, and if I solved 10000
    more of them I would never have to think more than I've already thought about it. (I don't like
    that...)


    So Surroundoku is /even easier/ than 3-In-A-Row!a (It's like 3- In-A-Row solvable only with rule 1!)

    Not my experience. I had several cracks at the 25x25 and gave up each time.


    I guess the only way to check here is for you to post a position where you're stuck, and we'll see
    if there are any "direct constraint" patterns that you've missed. (Such missings wouldn't be any
    patterns you've not thought about, just blind spots which we all get. Once I did a WordSearch
    puzzle and was convinced a particular word wasn't in the grid, but then my friend looked and saw it
    straight away - Doh!

    Mike.



    https://www.brainbashers.com/surroundokuhelp.asp

    The link doesn't work ... or the page was modified.


    Could someone briefly explain the rules?
    Is it like 3-In-A-Row, Tik-tak-toe, or Minimalist- GO, or Othello?

    Kevin has removed the link. Perhaps it will come back later on.

    There is a square grid of grey squares. Some of the squares contain a number.

    The objective is to mark each square black or white, satisfying the game constraints:

    1. If a square contains a number, that number must match the number of black
    squares in the "neighbourhood" of that square.

    2. Er, that's it I think.

    For a given square, its "neighbourhood" consists of the square itself, and all the adjacent squares
    either horizontally, vertically or diagonally. (Think: king's move in chess)

    So an interior square has 9 neighbours, an edge square has 6, and a corner square has 4.

    It's not like any of the games you list. More like MineSweeper, but instead of marking squares
    safe/mine, you mark them black/white, and the constraints to follow are a bit different but in some
    ways similar to minesweeper. [I think the key feature of the constraint (1) above, is it's
    localised nature. That's in common with how MineSweeper works.]

    Here's a sample puzzle on a 4x4 grid (using dots for empty squares)

    4 . . .
    . 5 2 .
    . . 4 .
    . 3 . .

    and its solution

    B B W W
    B B W W
    B W W W
    W B B B

    (When a square with a number is coloured black/white, its number is still visible in the square)

    Mike.



    Thank you... that's somewhat like Kakkuro (kakuro).

    or more like https://en.wikipedia.org/wiki/Light_Up_(puzzle)


    Or even more so like Hitori

    <https://www.brainbashers.com/hitori.asp>

    but the big difference is the /locality/ of the constraints. In Hitori the main constraint spreads
    influence right across a row or column, like a rook moving in chess. In Suroundoku the influence
    spreads more slowly like a king moving in chess.

    Mike.
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