novaBBS - rec.puzzles - Re: Pinocchio always lies -- says, "All my hats are green."

Re: Pinocchio always lies -- says, "All my hats are green."

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From: Pancho.J...@proton.me (Pancho)
Newsgroups: rec.puzzles
Subject: Re: Pinocchio always lies -- says, "All my hats are green."
Date: Tue, 28 Jun 2022 17:42:37 +0100
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by: Pancho - Tue, 28 Jun 2022 16:42 UTC

On 26/06/2022 20:14, henh...@gmail.com wrote:
> The 17th annual Brazilian Olympiad featured an incredibly tricky logic puzzle that went viral on social media. <------ Recently ? on Twitter ?
>
>
>
> Here's an interesting logic puzzle from MindYourDecisions:
>
>
>
> Assume that both of the following sentences are true:
>
> ------- Pinocchio always lies
> ------- Pinocchio says, "All my hats are green."
>
> What can we conclude from the above two statements:
>
> (A) Pinocchio has at least one hat.
> (B) Pinocchio has only one green hat.
> (C) Pinocchio has no hats.
> (D) Pinocchio has at least one green hat.
> (E) Pinocchio has no green hats.
>

(A). I don't understand why this is difficult? If he had no hats, the
statement would be vacuously true. So he must have at least one hat that
is not green.

Re: Pinocchio always lies -- says, "All my hats are green."

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Subject: Re: Pinocchio always lies -- says, "All my hats are green."
From: henha...@gmail.com (henh...@gmail.com)
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by: henh...@gmail.com - Tue, 28 Jun 2022 23:16 UTC

On Tuesday, June 28, 2022 at 9:42:45 AM UTC-7, Pancho wrote:
> On 26/06/2022 20:14, henh...@gmail.com wrote:
> > The 17th annual Brazilian Olympiad featured an incredibly tricky logic puzzle that went viral on social media.
<------ Recently ? on Twitter ?
> >
> >
> >
> > Here's an interesting logic puzzle from MindYourDecisions:
> >
> >
> >
> > Assume that both of the following sentences are true:
> >
> > ------- Pinocchio always lies
> > ------- Pinocchio says, "All my hats are green."
> >
> > What can we conclude from the above two statements:
> >
> > (A) Pinocchio has at least one hat.
> > (B) Pinocchio has only one green hat.
> > (C) Pinocchio has no hats.
> > (D) Pinocchio has at least one green hat.
> > (E) Pinocchio has no green hats.

> (A). I don't understand why this is difficult? If he had no hats, the
> statement would be vacuously true. So he must have at least one hat that is not green.

i understand that many Non-puzzle fans can never grok the [vacuously true] concept -- maybe it's related to the birth of modal logic.

in the actual test conditions, you have to get this right within 10 seconds (?) or so, so it's not super-easy.

https://en.wikipedia.org/wiki/American_Mathematics_Competitions
i can't quite figure out how this system (of selection, competition) changed from when i was young.

To program is to be.

interests / rec.puzzles / Re: Pinocchio always lies -- says, "All my hats are green."

Subject	Author
Re: Pinocchio always lies -- says, "All my hats are green."	Pancho
Re: Pinocchio always lies -- says, "All my hats are green."	henh...@gmail.com