I'm thinking of three sets (of bit-strings) which are conceptually infinite. Each of the sets is in practical use and has a name.--- Synchronet 3.21b-Linux NewsLink 1.2
Here are the first twelve elements of each set:
(A)
1
000
010
00100
00110
01100
01110
0010100
0010110
0011100
0011110
0110100
(B)
11
011
0011
1011
00011
10011
01011
000011
100011
010011
001011
101011
(C)
00
01
100
101
1100
1101
11100
11101
111100
111101
1111100
1111101
Each of the infinite sets has the same special and useful property.
__ What is that property? __
Please rot13 any solution.
Dearest regards. James Dow Allen (mail address: jamesdowallen at gmail)
I'm thinking of three sets (of bit-strings) which are conceptually infinite. Each of the sets is in practical use and has a name.
Here are the first twelve elements of each set:
(A)
1
000
010
00100
00110
01100
01110
0010100
0010110
0011100
0011110
0110100
(B)
11
011
0011
1011
00011
10011
01011
000011
100011
010011
001011
101011
(C)
00
01
100
101
1100
1101
11100
11101
111100
111101
1111100
1111101
Each of the infinite sets has the same special and useful property.
__ What is that property? __
Please rot13 any solution.
James Dow Allen <user4353@newsgrouper.org.invalid> posted:
I'm thinking of three sets (of bit-strings) which are conceptually infinite.
...
Each of the infinite sets has the same special and useful property.
__ What is that property? __
As a hint, I'll provide another puzzle! ... a
puzzle in the SAME DOMAIN as the original puzzle.
Guess the relevant domain and both puzzles may fall into place.
Transformation:
00 rRR 1
01 rRR 01
1 rRR 00
Comment: This .......... .... is essentially ....... over a binary ........ when the ........... .. . is a stationary 29%.
Question: What special property does this .......... .... have
which is quite rare among optimal .......... .....?
Apparently my puzzles were either too difficult or too boring. Please
post a reply, however brief, if you even read the puzzles.
Apparently my puzzles were either too difficult or too boring. Please
post a reply, however brief, if you even read the puzzles.
Cheers,
James
James Dow Allen <user4353@newsgrouper.org.invalid> posted:
I'm thinking of three sets (of bit-strings) which are conceptually infinite.
Each of the sets is in practical use and has a name.
Here are the first twelve elements of each set:
(A)
1 --> 1 ... 1/2
000 --> 3 ... 1/8
010 --> 3 ... 1/8 (or 1/2^3)
00100 \
00110 \
01100 / --> 5,5,5,5 ... 4/32 (or 4/2^5)
01110 /
0010100 \
0010110 \
0011100 / --> 7,7,7,7,7 ... 5/128 (or 5/2^7)
0011110 /
0110100 /
... 12358(B)
... 1235811 = 1 (always ignore the terminal 1; it is used as a "comma.")
011 = 2
0011 = 3
1011 = 1+3
00011 = 5
10011 = 1+5
01011 = 2+5
000011 = 8
100011 = 1+8
010011 = 2+8
001011 = 3+8
101011 = 1+3+8
(C)
00 = 0
01 = 1
100 = 2+0
101 = 2+1
1100 = 2+2+0
1101 = 2+2+1
11100 = 2+2+2+0
11101 = 2+2+2+1
111100 = 2+2+2+2+0
111101 = 2+2+2+2+1
1111100 = 2+2+2+2+2+0
1111101 = 2+2+2+2+2+1
Each of the infinite sets has the same special and useful property.
__ What is that property? __
James Dow Allen <user4353@newsgrouper.org.invalid> posted:
James Dow Allen <user4353@newsgrouper.org.invalid> posted:
I'm thinking of three sets (of bit-strings) which are conceptually infinite.
...
Each of the infinite sets has the same special and useful property.
__ What is that property? __
As a hint, I'll provide another puzzle! ... a
puzzle in the SAME DOMAIN as the original puzzle.
Guess the relevant domain and both puzzles may fall into place.
Transformation:
00 rRR 1
01 rRR 01
1 rRR 00
Comment: This .......... .... is essentially ....... over a binary ........ >> when the ........... .. . is a stationary 29%.
Question: What special property does this .......... .... have
which is quite rare among optimal .......... .....?
Apparently my puzzles were either too difficult or too boring.
Please post a reply, however brief, if you even read the puzzles.
Cheers,
James
On 26/02/2026 10:41, James Dow Allen wrote:
James Dow Allen <user4353@newsgrouper.org.invalid> posted:
James Dow Allen <user4353@newsgrouper.org.invalid> posted:
I'm thinking of three sets (of bit-strings) which are conceptually infinite.
...
Each of the infinite sets has the same special and useful property.
__ What is that property? __
Not boring at all, but... I don't always see an answer, especially a full answer, and time is
limited!...
So looking at your original post, I see some properties, but don't really have a full answer!
The sequences remind me of Huffman codes, and Huffman codes wouldn't work if sequences of them
couldn't be uniquely interpreted. Your sets have this property, so we could say they're like an
infinite set of Huffman codes(?).
Worded differently, all your sets seem to have the property that no two strings start with the same
prefix.
We could interpret them as finite nodes in an infinite binary tree, and each of these nodes
has the property that its path does not pass through any other nodes.
Also, it seems the sets of nodes are constructed (more or less) by some kind of fractal pattern.
E.g. set A seems to have a generator pattern (apart from the entry 1):
A
/ \
/ \
x x
/ \ / \
N A N A
where we paste the root A where it occurs below. The Ns are the terminal nodes, which are the ones
in your set A, which appears to be listed in order depth then left-to-right. (Left being
represented as 0, Right as 1).
I'd guess the sets might be related to compression of infinite stream data??? Perhaps used somehow
in video codecs? but I don't see exactly how, or know what their names would be.
Other observations: For all the sets there are infinite paths that have no prefix in the set. Set
A has uncountably many of these, e.g. 0010101010101... or 0111101011101... (basically, as long as
odd-numbered digits (other than the first) are 1). All the sets have "enough" nodes so that a
random path hits a node "almost certainly" (i.e. with probability 1). I don't know if that is
important.
But no end of other sets have these same properties - even if the "fractal" property is key. (I
suppose that might be important when processing an infinite stream, because only a finite amount of
context data would have to be maintained.
As a hint, I'll provide another puzzle! ... a
puzzle in the SAME DOMAIN as the original puzzle.
Guess the relevant domain and both puzzles may fall into place.
Transformation:
00 rRR 1
01 rRR 01
1 rRR 00
Question: What special property does this compaction code have
which is quite rare among optimal compaction codes?
(In my most recent post I suggested by example that the "Krafft sum"
was asymptotically one, where each token in the set contributes 2^(-k)
to the Krafft sum where k is the number of bits in that token.)
Mike Terry <news.dead.person.stones@darjeeling.plus.com> posted:
On 26/02/2026 10:41, James Dow Allen wrote:
James Dow Allen <user4353@newsgrouper.org.invalid> posted:
James Dow Allen <user4353@newsgrouper.org.invalid> posted:
Not boring at all, but... I don't always see an answer, especially a full answer, and time isI'm thinking of three sets (of bit-strings) which are conceptually infinite.
...
Each of the infinite sets has the same special and useful property.
__ What is that property? __
limited!...
So looking at your original post, I see some properties, but don't really have a full answer!
The sequences remind me of Huffman codes, and Huffman codes wouldn't work if sequences of them
couldn't be uniquely interpreted. Your sets have this property, so we could say they're like an
infinite set of Huffman codes(?).
Kudos to Mike Terry! These are exactly like Huffman codes; a more general term is compaction codes. In a finite world, no token will actually be infinite but it is convenient to define mappings of the integers which are unbounded.
A "Huffman code" is a compaction code which is optimal for some particular probability mass function. But EVERY compaction code with Krafft sum of one will be optimal for SOME distribution.
Worded differently, all your sets seem to have the property that no two strings start with the same
prefix.
Yes. These are called "prefix codes" or "prefix-free codes" or (old-fashioned term?) "instantaneous codes." Not all compaction codes
are instantaneous, cf arithmetic or quasi-arithmetic codes.
We could interpret them as finite nodes in an infinite binary tree, and each of these nodes
has the property that its path does not pass through any other nodes.
Also, it seems the sets of nodes are constructed (more or less) by some kind of fractal pattern.
E.g. set A seems to have a generator pattern (apart from the entry 1):
A
/ \
/ \
x x
/ \ / \
N A N A
where we paste the root A where it occurs below. The Ns are the terminal nodes, which are the ones
in your set A, which appears to be listed in order depth then left-to-right. (Left being
represented as 0, Right as 1).
I'd guess the sets might be related to compression of infinite stream data??? Perhaps used somehow
in video codecs? but I don't see exactly how, or know what their names would be.
Other observations: For all the sets there are infinite paths that have no prefix in the set. Set
A has uncountably many of these, e.g. 0010101010101... or 0111101011101... (basically, as long as
odd-numbered digits (other than the first) are 1). All the sets have "enough" nodes so that a
random path hits a node "almost certainly" (i.e. with probability 1). I don't know if that is
important.
Wow, and Kudos again. I think this is all correct.
But no end of other sets have these same properties - even if the "fractal" property is key. (I
suppose that might be important when processing an infinite stream, because only a finite amount of
context data would have to be maintained.
Yes. Kudos AGAIN to Mike!
For example, consider (B) where a token terminates if and only if a '11'
is encountered. There is a code with tokens terminating if and only if
a '111' is encountered. Or even a code which terminates at '1101010' !
I worked with these things back in the 20th century, so talking about them is a trip down Nostalgia Lane for me. PLEASE help me present puzzles better. Should I have provided more hints to start? Wait longer for responses?
The codes (A), (B), (C) have names. (B) is the "Fibonacci Code."
(C) is the "Golomb (or Golomb-Rice) Code with divisor 2."
I don't know the "official" name of (A) -- in fact I'd be unaware of it except that its co-inventor and I both consulted for the same company
in the mid-1990s. I will call (A) "a version of the Elias Gamma Code with
a palindromic property." Look again at (A); erase the 2nd, 4th, 6th bits, etc. The bit-strings left are all palindromes. (And Mike suggested this.) If a data stream is corrupted one can find a synchronization point and then decode BACKWARDS to the point of corruption, perhaps recovering all but one token.
FINALLY:
As a hint, I'll provide another puzzle! ... a
puzzle in the SAME DOMAIN as the original puzzle.
Guess the relevant domain and both puzzles may fall into place.
Transformation:
00 rRR 1
01 rRR 01
1 rRR 00
The coded-token set {1, 01, 00} is a simple prefix code, satisfying the Krafft Equality
1/2 + 1/4 + 1/4 = 1.
(BTW, for this and similar codes if the input data ends with an odd number
of 0's an extra 0 is injected at the end and later removed during decompaction.)
(The LENGTH of input data is generally knowable.)
Comment: This compaction code is essentially optimal over a binary alphabet when the probability of '1' is a stationary 29%.
STILL UNSPOILED:
Question: What special property does this compaction code have
which is quite rare among optimal compaction codes?
Cheers,
James
I worked with these things back in the 20th century, so talking about
them is a trip down Nostalgia Lane for me. PLEASE help me present
puzzles better. Should I have provided more hints to start? Wait longer
for responses?
Would it be practical to provide a real-World, or 'puzzle-World', scenario where the sequences, with the given properties, provide a solution to a problem the inhabitants faced? Crash survivors, on two islands, communicating with limited means - that sort of thing... I find that understanding a problem gives weight to the solution.
I like pictures and there is a nice one (possibly related) here:
https://en.wikipedia.org/wiki/Zeckendorf%27s_theorem
STILL UNSPOILED:
Question: What special property does the compaction code [shown below] have
which is quite rare among optimal compaction codes?
Mike Terry <news.dead.person.stones@darjeeling.plus.com> posted:--- Synchronet 3.21d-Linux NewsLink 1.2
On 26/02/2026 10:41, James Dow Allen wrote:
James Dow Allen <user4353@newsgrouper.org.invalid> posted:
James Dow Allen <user4353@newsgrouper.org.invalid> posted:
FINALLY:
As a hint, I'll provide another puzzle! ... a
puzzle in the SAME DOMAIN as the original puzzle.
Guess the relevant domain and both puzzles may fall into place.
Transformation:
00 rRR 1
01 rRR 01
1 rRR 00
Comment: This compaction code is essentially optimal over a binary alphabet when the probability of '1' is a stationary 29%.
STILL UNSPOILED:
Question: What special property does this compaction code have
which is quite rare among optimal compaction codes?
Cheers,
James
Just a reminder that one puzzle has not yet been explicitly solved. The "puzzle" isn't difficult, but stating the solution should elicit at
least a tiny "WOW!"
In general, in this puzzle, we could be talking about reducing the size
of source code for very constrained computer architectures; is that
correct?
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