OK, a friend just emailed me a puzzle I sent him about 28 years ago.
Enjoy, and by now I believe I've already heard every possible 'cheat',
so try to stick with 'correct' answers if possible. I do have the 17
minute solution, and it was surprisingly easy once I figured out the
'trick', which doesn't require violating any of the stated or even
unstated conditions (they do not have a rope, or a boat, or any
machinery, etc.)..
Subject: Puzzler
Date: Tue, 14 Apr 1998 12:18:59 -0500
A little brain teaser for your amusement. This puzzler comes from Bob
Pease's column on page 144 in the April 6th 1998 issue of Electronic
Design magazine. (I do not know the answer.) Four guys named Ari,
Ben, Cal, and Don have to cross a bridge. But the bridge is only
strong enough to hold two men at a time. It's dark outside, and they
have only one flashlight. If two guys cross using the flashlight,
one guy will have to come back carrying the flashlight. (They cannot
throw the flashlight across the bridge.) Ari takes one minute to
cross, Ben is slower at two minutes; Cal is slower at five minutes;
and Don is very slow at 10 minutes. They all have to make it across
in 17 minutes. The problem is given to Earl and Fran. Earl soon
figures out that the best answer is 19 minutes. Fran says she knows
the way to get everybody across in 17 minutes. How is that possible?
My answer in my email to Bob Pease was: wait till morning... he did
not like my answer.
On Thu, 29 Jan 2026 20:21:31 -0000 (UTC), Mark Olson
<olsonm@tiny.invalid> wrote:
A little brain teaser for your amusement. This puzzler comes from Bob
Pease's column on page 144 in the April 6th 1998 issue of Electronic
Design magazine. (I do not know the answer.) Four guys named Ari,
Ben, Cal, and Don have to cross a bridge. But the bridge is only
strong enough to hold two men at a time. It's dark outside, and they
have only one flashlight. If two guys cross using the flashlight,
one guy will have to come back carrying the flashlight. (They cannot
throw the flashlight across the bridge.) Ari takes one minute to
cross, Ben is slower at two minutes; Cal is slower at five minutes;
and Don is very slow at 10 minutes. They all have to make it across
in 17 minutes. The problem is given to Earl and Fran. Earl soon
figures out that the best answer is 19 minutes. Fran says she knows
the way to get everybody across in 17 minutes. How is that possible?
Doesn't Ari carry the others?
Mark Roberts <mark@markr.myzen.co.uk> wrote:
On Thu, 29 Jan 2026 20:21:31 -0000 (UTC), Mark Olson
<olsonm@tiny.invalid> wrote:
A little brain teaser for your amusement. This puzzler comes from Bob
Pease's column on page 144 in the April 6th 1998 issue of Electronic
Design magazine. (I do not know the answer.) Four guys named Ari,
Ben, Cal, and Don have to cross a bridge. But the bridge is only
strong enough to hold two men at a time. It's dark outside, and they
have only one flashlight. If two guys cross using the flashlight,
one guy will have to come back carrying the flashlight. (They cannot
throw the flashlight across the bridge.) Ari takes one minute to
cross, Ben is slower at two minutes; Cal is slower at five minutes;
and Don is very slow at 10 minutes. They all have to make it across
in 17 minutes. The problem is given to Earl and Fran. Earl soon
figures out that the best answer is 19 minutes. Fran says she knows
the way to get everybody across in 17 minutes. How is that possible?
Doesn't Ari carry the others?
Full marks for a good solution, which did not violate any of the
_explicit_ conditions, and would certainly take the least time.
So we need to add another constraint: each man must cross by walking
on his own two feet.
OK, a friend just emailed me a puzzle I sent him about 28 years ago.
Enjoy, and by now I believe I've already heard every possible 'cheat',
so try to stick with 'correct' answers if possible. I do have the 17
minute solution, and it was surprisingly easy once I figured out the
'trick', which doesn't require violating any of the stated or even
unstated conditions (they do not have a rope, or a boat, or any
machinery, etc.)..
Subject: Puzzler
Date: Tue, 14 Apr 1998 12:18:59 -0500
A little brain teaser for your amusement. This puzzler comes from Bob
Pease's column on page 144 in the April 6th 1998 issue of Electronic
Design magazine. (I do not know the answer.) Four guys named Ari,
Ben, Cal, and Don have to cross a bridge. But the bridge is only
strong enough to hold two men at a time. It's dark outside, and they
have only one flashlight. If two guys cross using the flashlight,
one guy will have to come back carrying the flashlight. (They cannot
throw the flashlight across the bridge.) Ari takes one minute to
cross, Ben is slower at two minutes; Cal is slower at five minutes;
and Don is very slow at 10 minutes. They all have to make it across
in 17 minutes. The problem is given to Earl and Fran. Earl soon
figures out that the best answer is 19 minutes. Fran says she knows
the way to get everybody across in 17 minutes. How is that possible?
My answer in my email to Bob Pease was: wait till morning... he did
not like my answer.
On 29/01/2026 20:21, Mark Olson wrote:
OK, a friend just emailed me a puzzle I sent him about 28 years ago.
Enjoy, and by now I believe I've already heard every possible 'cheat',
so try to stick with 'correct' answers if possible. I do have the 17
minute solution, and it was surprisingly easy once I figured out the
'trick', which doesn't require violating any of the stated or even
unstated conditions (they do not have a rope, or a boat, or any
machinery, etc.)..
Subject: Puzzler
Date: Tue, 14 Apr 1998 12:18:59 -0500
A little brain teaser for your amusement. This puzzler comes from Bob
Pease's column on page 144 in the April 6th 1998 issue of Electronic
Design magazine. (I do not know the answer.) Four guys named Ari,
Ben, Cal, and Don have to cross a bridge. But the bridge is only
strong enough to hold two men at a time. It's dark outside, and they
have only one flashlight. If two guys cross using the flashlight,
one guy will have to come back carrying the flashlight. (They cannot
throw the flashlight across the bridge.) Ari takes one minute to
cross, Ben is slower at two minutes; Cal is slower at five minutes;
and Don is very slow at 10 minutes. They all have to make it across
in 17 minutes. The problem is given to Earl and Fran. Earl soon
figures out that the best answer is 19 minutes. Fran says she knows
the way to get everybody across in 17 minutes. How is that possible?
My answer in my email to Bob Pease was: wait till morning... he did
not like my answer.
Don and Ari set out across the bridge. Halfway across, Ari stops, and
shines the flashlight for Don to finish the crossing. He then shines the flashlight for one of the other two to cross, and finally for the last
one, accompanying him across the bridge after the halfway point.
Enjoy, and by now I believe I've already heard every possible 'cheat',
so try to stick with 'correct' answers if possible. I do have the 17
minute solution, and it was surprisingly easy once I figured out the
'trick', which doesn't require violating any of the stated or even
unstated conditions (they do not have a rope, or a boat, or any
machinery, etc.)..
On Jan 29, 2026 at 3:21:31 PM EST, "Mark Olson" <olsonm@tiny.invalid> wrote:
Enjoy, and by now I believe I've already heard every possible 'cheat',
so try to stick with 'correct' answers if possible. I do have the 17
minute solution, and it was surprisingly easy once I figured out the
'trick', which doesn't require violating any of the stated or even
unstated conditions (they do not have a rope, or a boat, or any
machinery, etc.)..
Thread-merge.
Instead of wasting my brain on this, I asked ChatGPT.
There is no trick involving hidden assumptions or extra people. Earl is simply
wrong.
The standard optimal strategy gets them across in exactly 17 minutes. Fran has
spotted it.
Mark Roberts <mark@markr.myzen.co.uk> wrote:
On Thu, 29 Jan 2026 20:21:31 -0000 (UTC), Mark Olson
<olsonm@tiny.invalid> wrote:
A little brain teaser for your amusement. This puzzler comes from Bob
Pease's column on page 144 in the April 6th 1998 issue of Electronic
Design magazine. (I do not know the answer.) Four guys named Ari,
Ben, Cal, and Don have to cross a bridge. But the bridge is only
strong enough to hold two men at a time. It's dark outside, and they
have only one flashlight. If two guys cross using the flashlight,
one guy will have to come back carrying the flashlight. (They cannot
throw the flashlight across the bridge.) Ari takes one minute to
cross, Ben is slower at two minutes; Cal is slower at five minutes;
and Don is very slow at 10 minutes. They all have to make it across
in 17 minutes. The problem is given to Earl and Fran. Earl soon
figures out that the best answer is 19 minutes. Fran says she knows
the way to get everybody across in 17 minutes. How is that possible?
Doesn't Ari carry the others?
Full marks for a good solution, which did not violate any of the
_explicit_ conditions, and would certainly take the least time.
So we need to add another constraint: each man must cross by walking
on his own two feet.
On Thu, 29 Jan 2026 21:42:16 -0000 (UTC), Mark Olson
<olsonm@tiny.invalid> wrote:
Mark Roberts <mark@markr.myzen.co.uk> wrote:
On Thu, 29 Jan 2026 20:21:31 -0000 (UTC), Mark Olson
<olsonm@tiny.invalid> wrote:
A little brain teaser for your amusement. This puzzler comes from Bob >>>> Pease's column on page 144 in the April 6th 1998 issue of Electronic
Design magazine. (I do not know the answer.) Four guys named Ari,
Ben, Cal, and Don have to cross a bridge. But the bridge is only
strong enough to hold two men at a time. It's dark outside, and they
have only one flashlight. If two guys cross using the flashlight,
one guy will have to come back carrying the flashlight. (They cannot
throw the flashlight across the bridge.) Ari takes one minute to
cross, Ben is slower at two minutes; Cal is slower at five minutes;
and Don is very slow at 10 minutes. They all have to make it across
in 17 minutes. The problem is given to Earl and Fran. Earl soon
figures out that the best answer is 19 minutes. Fran says she knows
the way to get everybody across in 17 minutes. How is that possible?
Doesn't Ari carry the others?
Full marks for a good solution, which did not violate any of the
_explicit_ conditions, and would certainly take the least time.
So we need to add another constraint: each man must cross by walking
on his own two feet.
Ari and ben cross in 2 minutes
Throw the flashlight back over.
Cal is over in 5 so its now 7 minutes
Throw the flash light over.
Don makes it in 10 so 17 minutes.
Ugh. I _need_ to 'waste' brain power to keep it supple- no day to
day job to keep the little gray cells active, you see.
On Jan 29, 2026 at 8:44:43 PM EST, "Mark Olson" <olsonm@tiny.invalid> wrote:
Ugh. I _need_ to 'waste' brain power to keep it supple- no day to
day job to keep the little gray cells active, you see.
I play a little chess, and do the "Quartiles" puzzles in Apple News, which I find quite good fun.
I have never learned to play chess!
But then again, I've never learned
to juggle, play a stringed instrument, paint with oils, or a million
and one other things.
Instead of wasting my brain on this, I asked ChatGPT.
tickI play a little chess, and do the "Quartiles" puzzles in Apple News, which I >> find quite good fun.
I have never learned to play chess!
But then again, I've never learned to juggle,tick
play a stringed instrument,tick
paint with oils,I subbed that out to my wife :-)
or a million and one other thingsA million and one? Do you have a list, please?
<swerve to other thread>
But as none of us think ChatGPT is a reasoning engine, how did it get
the answer? Is not the most likely way that, trained on millions of
internet pages, it already knew it somewhere, and just regurgitated
it? In which case "I asked ChatGPT" becomes "I asked the internet"?
I pasted the problem exactly as stated by Mark into a search engine,
and found dozens of hits, including Wikipedia. So ChatGPT didn't
*solve* the problem, it just searched for the answer and formatted it
nicely for you.
On Feb 1, 2026 at 5:05:34 AM EST, "Champ" <neal@champ.org.uk> wrote:
<swerve to other thread>
But as none of us think ChatGPT is a reasoning engine, how did it get
the answer? Is not the most likely way that, trained on millions of
internet pages, it already knew it somewhere, and just regurgitated
it? In which case "I asked ChatGPT" becomes "I asked the internet"?
I pasted the problem exactly as stated by Mark into a search engine,
and found dozens of hits, including Wikipedia. So ChatGPT didn't
*solve* the problem, it just searched for the answer and formatted it
nicely for you.
Correct. In this case, it matched the words in approximately the right order >(with a score probability of next word algo), and found related text including >words that would indicate a correct solution to a problem. but even this has >value over old-fashioned google. When you google, you get sites solely created >to generate ad revenue. You get endless forums on vBulletin platforms (is >there a more hateful user interface for that use case?) - on which as many >anwers are wrong as are right. You get imprecise results because google is so >literal (GSX-R1000, GSXR1000, GSXR-1000, GSX-R 1000, etc)
Chat GPT is so much more than a search engine. It can organize, collate, sort, >filter, rank, and find logic. Here's something I did yesterday. I've found an >engine for K's cobra. It's engine only but I know the gearbox I want, so I >need to get a water pump, a fuel pump, carbs or EFI, a flywheel, clutch, and >bellhousing...all of which needs to be compatible with each other. ChatGPT >found all the options, organized them, asked questions about the planned usage >of the car, and created a recommendation summary with costs and trade-offs. I >took the #1 reco to a friend who has built 100 engines, and he said "yeah, >solid set of choices, order those". I could never have got to the answer on >google alone, plus it would have been a miserable experience.
I took the #1 reco to a friend who has built 100 engines, and he said "yeah, solid set of choices, order those". I could never have got to the answer on google alone, plus it would have been a miserable experience.
Ben Blaney wrote:
I took the #1 reco to a friend who has built 100 engines, and he said "yeah, >> solid set of choices, order those". I could never have got to the answer on >> google alone, plus it would have been a miserable experience.
You needed to ask an expert to verify the answers though, in case
ChatGPT had just made it up.
You could have just asked your friend and saved a step.
On 01/02/2026 15:45, Ben Blaney wrote:
On Feb 1, 2026 at 5:05:34 AM EST, "Champ" <neal@champ.org.uk> wrote:
<swerve to other thread>
But as none of us think ChatGPT is a reasoning engine, how did it get
the answer?-a Is not the most likely way that, trained on millions of
internet pages, it already knew it somewhere, and just regurgitated
it?-a In which case "I asked ChatGPT" becomes "I asked the internet"?
I pasted the problem exactly as stated by Mark into a search engine,
and found dozens of hits, including Wikipedia.-a So ChatGPT didn't
*solve* the problem, it just searched for the answer and formatted it
nicely for you.
Correct. In this case, it matched the words in approximately the right
order
(with a score probability of next word algo), and found related text
including
words that would indicate a correct solution to a problem. but even
this has
value over old-fashioned google. When you google, you get sites solely
created
to generate ad revenue. You get endless forums on vBulletin platforms (is
there a more hateful user interface for that use case?) - on which as
many
anwers are wrong as are right. You get imprecise results because
google is so
literal (GSX-R1000, GSXR1000, GSXR-1000, GSX-R 1000, etc)
Chat GPT is so much more than a search engine. It can organize,
collate, sort,
filter, rank, and find logic. Here's something I did yesterday. I've
found an
engine for K's cobra. It's engine only but I know the gearbox I want,
so I
need to get a water pump, a fuel pump, carbs or EFI, a flywheel,
clutch, and
bellhousing...all of which needs to be compatible with each other.
ChatGPT
found all the options, organized them, asked questions about the
planned usage
of the car, and created a recommendation summary with costs and trade-
offs. I
took the #1 reco to a friend who has built 100 engines, and he said
"yeah,
solid set of choices, order those". I could never have got to the
answer on
google alone, plus it would have been a miserable experience.
Quite. I won't elaborate with the shenanigans Ive just had with both Claude and Chatgpt trying to trap JavaScript errors in a page that refreshes data from a VB app that refreshes data from an Excel worksheet that gets it's
data from A timing equipment emulator that gets it's data from a log file that a Claude python script created
<swerve to other thread>
But as none of us think ChatGPT is a reasoning engine, how did it get
the answer? Is not the most likely way that, trained on millions of
internet pages, it already knew it somewhere, and just regurgitated
it? In which case "I asked ChatGPT" becomes "I asked the internet"?
I pasted the problem exactly as stated by Mark into a search engine,
and found dozens of hits, including Wikipedia. So ChatGPT didn't
*solve* the problem, it just searched for the answer and formatted it
nicely for you.
Correct. In this case, it matched the words in approximately the right order >(with a score probability of next word algo), and found related text including >words that would indicate a correct solution to a problem. but even this has >value over old-fashioned google. When you google, you get sites solely created >to generate ad revenue
On Sun, 1 Feb 2026 15:45:23 -0000 (UTC), Ben Blaney
When you google, you get sites solely created
to generate ad revenue
Which is why I haven't used google for some time now
Champ wrote:
On Sun, 1 Feb 2026 15:45:23 -0000 (UTC), Ben Blaney
When you google, you get sites solely created
to generate ad revenue
Which is why I haven't used google for some time now
Quite. It's by design, since Google gets the ad revenue. >https://www.wheresyoured.at/the-men-who-killed-google/
I don't think you can Justify the use of AI agents because of the enshitification of internet searchJust to be clear, I am 100% not doing that.
Quite often nowadays I go straight to Wikipedia if I want a specificAgreed.... and they are currently fighting to prevent being overrun by
fact. And I send them a few quid a month. Wikipedia is one of the
last bastions of the benefits of the internet we were sold 30 years
ago
Quite often nowadays I go straight to Wikipedia if I want a specific
fact. And I send them a few quid a month. Wikipedia is one of the
last bastions of the benefits of the internet we were sold 30 years
ago
On Tue, 03 Feb 2026 08:03:12 +0000, Sqirrel99+1
<secret.sqirrel99@gmail.com> wrote:
Champ wrote:
On Sun, 1 Feb 2026 15:45:23 -0000 (UTC), Ben Blaney
When you google, you get sites solely created
to generate ad revenue
Which is why I haven't used google for some time now
Quite. It's by design, since Google gets the ad revenue.
https://www.wheresyoured.at/the-men-who-killed-google/
Prime example of enshitification
I don't think you can Justify the use of AI agents because of the enshitification of internet search
Quite often nowadays I go straight to Wikipedia if I want a specific
fact. And I send them a few quid a month. Wikipedia is one of the
last bastions of the benefits of the internet we were sold 30 years
ago
On 03/02/2026 09:45, Champ wrote:[Citation needed].
Wikipedia is one of the last bastions of the benefits
of the internet we were sold 30 years ago
Yet they are not always a "trusted" source.
Champ wrote:Wikipedia is one of the last bastions of the benefits
of the internet we were sold 30 years ago
Yet they are not always a "trusted" source.
If in doubt I try and find another site to confirm any details.Any fact that wikipedia publishes should cite a canonical published source;
On Jan 29, 2026 at 3:21:31 PM EST, "Mark Olson" <olsonm@tiny.invalid> wrote:
Enjoy, and by now I believe I've already heard every possible 'cheat',
so try to stick with 'correct' answers if possible. I do have the 17
minute solution, and it was surprisingly easy once I figured out the
'trick', which doesn't require violating any of the stated or even
unstated conditions (they do not have a rope, or a boat, or any
machinery, etc.)..
Thread-merge.
Instead of wasting my brain on this, I asked ChatGPT.
There is no trick involving hidden assumptions or extra people. Earl is simply
wrong.
The standard optimal strategy gets them across in exactly 17 minutes. Fran has
spotted it.
The key idea is that the two fastest people act as rCLshuttlesrCY for the flashlight, minimizing the expensive return trips.
Sequence:
Ari (1 min) and Ben (2 min) cross together.
Time elapsed: 2 minutes.
Ari returns alone with the flashlight.
Time elapsed: 1 minute (total 3).
Cal (5 min) and Don (10 min) cross together.
Time elapsed: 10 minutes (total 13).
Ben returns alone with the flashlight.
Time elapsed: 2 minutes (total 15).
Ari and Ben cross together again.
Time elapsed: 2 minutes (total 17).
Everyone is across in 17 minutes.
Quite often nowadays I go straight to Wikipedia if I want a specific
fact. And I send them a few quid a month. Wikipedia is one of the
last bastions of the benefits of the internet we were sold 30 years
ago
On 30/01/2026 00:43, Ben Blaney wrote:
Sequence:
Ari (1 min) and Ben (2 min) cross together.
Time elapsed: 2 minutes.
Ari returns alone with the flashlight.
Time elapsed: 1 minute (total 3).
Cal (5 min) and Don (10 min) cross together.
Time elapsed: 10 minutes (total 13).
Ben returns alone with the flashlight.
Time elapsed: 2 minutes (total 15).
Ari and Ben cross together again.
Time elapsed: 2 minutes (total 17).
Everyone is across in 17 minutes.
So the flashlight is completely irrelevant then, except as a baton.
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