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When Is Cheryl's Birthday?

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Re: When Is Cheryl's Birthday?

#121

Post by anigbrowl »

sukilot wrote: post #118
Nursie wrote: post #108

Earlier quoted context omitted.

If we take silence as indicative of lack of knowledge, then nobody needs to speak. Bernard: Silence (he doesn't know the answer) Albert: Silence (he doesn't either) Bernard: I know it! Interestingly it then becomes relevant who was silent first . Basically it's nonsense.

If you assume Albert and Bernard are identical computers running identical programs, then it isn't nonsense. And that's not just a gimmick , timing analysis is how some side-channel attacks work in crypto.

Thank you.

Re: When Is Cheryl's Birthday?

#122

Post by chongli »

baddox wrote: post #112
chongli wrote: post #80

Earlier quoted context omitted.

The hard part is not the logic, it's actually figuring out that this is a logic puzzle that needs to be solved by deduction and not a bunch of nonsense with terrible grammar. To borrow your Ode To Joy example, it's like trying to learn to play the piece after the sheet music had been torn and tattered, burned and stained with coffee. Sure, the music is simple once you get past all of the garbage in your way. The orig…

> The hard part is not the logic, it's actually figuring out that this is a logic puzzle that needs to be solved by deduction and not a bunch of nonsense with terrible grammar. I am seeing this claim a lot, but I do not understand it. Why would readers assume that a riddle is a bunch of nonsense, rather than something with an objective answer? > To borrow your Ode To Joy example, it's like trying to learn to play the…

I am seeing this claim a lot, but I do not understand it. Why would readers assume that a riddle is a bunch of nonsense, rather than something with an objective answer?

Different people carry different assumptions with them throughout their lives. Not everybody approaches a logic puzzle with the mental preparation of solving logic puzzles. They aren't looking to analyze the statements and they don't carry the assumption that the statements carry just enough information to solve it. Instead, they might expect some trick or play on words to give a "stupid" answer.

because I had no trouble understanding the wording of the puzzle

But you do have trouble understanding that other people might be different from you; with different experiences, assumptions, etc.

Re: When Is Cheryl's Birthday?

#123

Post by Nursie »

sukilot wrote: post #118
Nursie wrote: post #108

Earlier quoted context omitted.

If we take silence as indicative of lack of knowledge, then nobody needs to speak. Bernard: Silence (he doesn't know the answer) Albert: Silence (he doesn't either) Bernard: I know it! Interestingly it then becomes relevant who was silent first . Basically it's nonsense.

If you assume Albert and Bernard are identical computers running identical programs, then it isn't nonsense. And that's not just a gimmick , timing analysis is how some side-channel attacks work in crypto.

Of course it's nonsense.

If we can deduce the answer from silence then there's no need for any of the information given in the question, it's not a logic puzzle it's bullshit.

I don't assume Albert and Bernard are anything, if you've made assumptions beyond what's stated in the question then you've done it wrong.

And yes, I understand timing oracles.

Re: When Is Cheryl's Birthday?

#124

Post by Nursie »

andrewprock wrote: post #50
logicallee wrote: post #38

Earlier quoted context omitted.

can you make your whole comment more explicit, I don't follow your objection.

Let's consider the question: 1. "Why did Albert speak first?" Before we answer this, we need to develop a set of assumptions to operate under. Given the synthetic nature of the problem, we might assume that both Albert and Bernard are of equal ability, and able to make logical inferences based on reasonable assumptions. We'll also assume that both Albert and Bernard are only going to announce the binary state of each…

>> Let's consider the question: 1. "Why did Albert speak first?"

If you're even thinking about this then you have failed the question, it's a puzzle that asks you to derive a correct answer from the data provided, not from your conjectures about human behaviour.

Re: When Is Cheryl's Birthday?

#125

Post by Nursie »

If you're puzzling over this you've done it wrong.

There is no inference from silence. There is no humanity in such a question, there is simply the information you're given and the application of logic to narrow down the answers. The Singaporean kids that took the exam knew this and anyone that's ever taken a maths or logic exam should know this.

You don't guess what might have happened from human behaviour because you don't know, you don't look for a 'trick' to give away the answer, you simply use the data in the question to narrow down the possibilities until you can arrive at an answer.

The moment you think "but what if this action could have taken place because if he knew he would have said" you have failed.

And you probably suck at debugging.

Re: When Is Cheryl's Birthday?

#126

Post by Nursie »

andrewprock wrote: post #59
logicallee wrote: post #55

Earlier quoted context omitted.

Albert speaks first because he's Albert! They're obviously just going alphabetically. Maybe my other comment was right and they should have been called Alice, Bob, and Carol. The way I read the question, it's as though a moderator said: "Albert, tell me what's on your mind." "Bernard?" "Albert?" I will add that #4 should certainly be in the past tense ("at first I didn't know") because this way Albert and Bernard are…

I believe assuming they are "just going alphabetically" and/or that there is some sort of implicit moderator managing the conversation qualify as non-obvious assumptions.

Assume nothing, simply take what's stated. This happened and then this and then this.

If you can't piece everything together then... well you're not suited to logical analysis.

Re: When Is Cheryl's Birthday?

#127

Post by logicallee »

malisper wrote: post #86
logicallee wrote: post #36

Earlier quoted context omitted.

I don't know, can code like this reason about knowledge-about-knowledge in general? For example, can a version of the code be used to solve the 'hardest puzzle' - https://xkcd.com/blue_eyes.html (solution: https://xkcd.com/solution.html ) ?

It can. If you know someone else doesn't know, that just gives you more knowledge you yourself can use. For the "hardest puzzle", on each day everyone learns that no one was able to figure out the solution the day before. Because of this, a person knows that for a possible number of blue-eyed people to be valid, a person who sees one less blue eyed person than that, must have been unable to figure it out on the previ…

I don't have Lisp, can you link to a pastebin e.g. at https://ideone.com/ that runs it?

Re: When Is Cheryl's Birthday?

#128

Post by andrewprock »

Nursie wrote: post #126
andrewprock wrote: post #59

Earlier quoted context omitted.

I believe assuming they are "just going alphabetically" and/or that there is some sort of implicit moderator managing the conversation qualify as non-obvious assumptions.

Assume nothing, simply take what's stated. This happened and then this and then this. If you can't piece everything together then... well you're not suited to logical analysis.

On the contrary, logical analysis is generally not well suited to the understanding of human behavior.

Re: When Is Cheryl's Birthday?

#130

Post by Nursie »

andrewprock wrote: post #128
Nursie wrote: post #126

Earlier quoted context omitted.

Assume nothing, simply take what's stated. This happened and then this and then this. If you can't piece everything together then... well you're not suited to logical analysis.

On the contrary, logical analysis is generally not well suited to the understanding of human behavior.

If you think this is a question about human behaviour then you've gone very wrong indeed.
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