Daily Challenges

[Paddy]

59 minutes ago, Peckris 2 said:

Anyone?

Isn't it something like "Everything I say is a lie"? This leaves it impossible for the Cannibal!

 

[Peckris 2]

1 hour ago, jelida said:

He could say “you’re going to boil me alive” ; that would provide the chief with an unresolvable conundrum.

Jerry

That's more or less it. I'll try to think of a harder one next time!

[Peckris 2]

11 minutes ago, Paddy said:

Isn't it something like "Everything I say is a lie"? This leaves it impossible for the Cannibal!

That's another solution. Too easy!

[DaveG38]

1 hour ago, Peckris 2 said:

That's no good. If it was the truthful robot, you'd get the answer 'yes', but you'd also get the answer 'yes' from the lying robot if it WASN'T the safe door, so you'd be no better off.

This is how it works. Point to one door and ask each robot the question 'if I ask you if this is the door to safety would you say yes.'  Assume the door I point to is the safe one. The truthful robot will simply say yes, he would say this because it is true. The lying robot says to himself, I know that the door pointed to is the safe one, but because I'm a liar I would say no. But then the rest of the question asks whether he would say yes to his own lying answer. Logically, the robot being a liar will directly contradict his earlier 'no' answer so he says yes to the question, since he is lying about his own earlier lie. Hence both robots indicate which is the correct door and so you can escape. Works the other way round for the wrong door.

This has always been my understanding of the puzzle, but if anybody knows different please say.

 

PS: Missed the answers already given, which have a greater logic. My answer was predicated on a slightly different version, whereby a man is walking through the jungle and comes to a fork in the road. There is a native at the fork. One arm of the fork leads to safety and the other to certain death in the alligator swamp. The man knows that some natives always lie and others always tell the truth, but there is no way he can determine which type of native he has encountered. As before what one question can he ask to determine the way to safety?

Edited April 1, 2020 by DaveG38

[terrysoldpennies]

How about an easier one .     What will go up a chimney down but won't go down a chimney up   ?

[Paddy]

23 minutes ago, terrysoldpennies said:

How about an easier one .     What will go up a chimney down but won't go down a chimney up   ?

An umbrella?

 

[terrysoldpennies]

1 minute ago, Paddy said:

An umbrella?

 

[Peckris 2]

2 hours ago, DaveG38 said:

This is how it works. Point to one door and ask each robot the question 'if I ask you if this is the door to safety would you say yes.'  Assume the door I point to is the safe one. The truthful robot will simply say yes, he would say this because it is true. The lying robot says to himself, I know that the door pointed to is the safe one, but because I'm a liar I would say no. But then the rest of the question asks whether he would say yes to his own lying answer. Logically, the robot being a liar will directly contradict his earlier 'no' answer so he says yes to the question, since he is lying about his own earlier lie. Hence both robots indicate which is the correct door and so you can escape. Works the other way round for the wrong door.

"You are allowed just one question to one of the robots".

Your version allows a question to each robot which is not allowed.

[blakeyboy]

I always check on my video system in the big workshop what's on that channel.

I recorded  off that channel a 10 minute wartime public information film on how to deal with incendiary bombs that fall through your roof.

Very interesting- made much more so for me, since it starred Will Hay!!!

[Diaconis]

3 minutes ago, blakeyboy said:

I always check on my video system in the big workshop what's on that channel.

I recorded  off that channel a 10 minute wartime public information film on how to deal with incendiary bombs that fall through your roof.

Very interesting- made much more so for me, since it starred Will Hay!!!

Oh Mr. Blakey

[Diaconis]

Enough of robots, here’s an easier version I use and  you can do in real life. Again with a numismatic flavour.

You need two spectators.

Give them a coin and tell them that one is to lie and the other is to tell the truth. Turn your back to them and let them decide on who will be the liar and who will hold the coin.

You turn around and ask one question to either person and you know who holds the coin. 

Same principle so it should be easy.

Whats the question?

[Paddy]

Here is another old chestnut:

Arrange 6 coins as per the top picture. You have 3 moves to get to the bottom picture. In each move you can slide just one coin - it must not move any other coin in sliding and must come to rest so that it is touching two or more other coins. How do you do it?

[Peckris 2]

Question - must the dates be as you've shown, or is it just that you must convert 2 rows into a circle, i.e. any old dates?

[Paddy]

No worry about the dates - just the circle shape.

I put them in so I/you can describe the moves. It is trickier than it looks - best to try with coins on a table.

 

[DaveG38]

16 hours ago, Peckris 2 said:

"You are allowed just one question to one of the robots".

Your version allows a question to each robot which is not allowed.

No, it doesn't matter whether you ask the lying robot or the truthful one. The answer is the same. I was simply illustrating this for both types not assuming two questions.

[Diaconis]

Maybe this one will elicit a response.

Referring to the layout below, the problem is to draw a line connecting the 3's, a separate line connecting the 2's and a separate line connecting the Aces.

You can't cross any line and you cant go out of the layout or cross over any card.

 

 

[Diaconis]

On 4/1/2020 at 8:12 PM, Paddy said:

Here is another old chestnut:

Arrange 6 coins as per the top picture. You have 3 moves to get to the bottom picture. In each move you can slide just one coin - it must not move any other coin in sliding and must come to rest so that it is touching two or more other coins. How do you do it?

Paddy, please put me out of my misery, I've got it down to four but three seems impossible, thx

[Diaconis]

And finally Esther

The Queen can move any number of squares horizontally, vertically, or diagonally but must cover all 9 of the shaded corner squares in 4 moves. An old chestnut in another guise.

[Diaconis]

This one was inspired by one of our members.

What's the top view?

[Paddy]

45 minutes ago, Diaconis said:

Paddy, please put me out of my misery, I've got it down to four but three seems impossible, thx

I warned you it was not easy! Using the dates on the coins for ref:

1. 1914 slides to above 1913 and 1912

2. 1913 slides to above 1917 and 1967

3. 1917 slides to fill the gap between 1914 and 1913.

Most people, even after being shown it, start by moving 1912 (or 1917) first, and then it is impossible.

 

[Sword]

Hey, I am just about to post the answer:

[Sword]

[Paddy]

16 minutes ago, Diaconis said:

And finally Esther

The Queen can move any number of squares horizontally, vertically, or diagonally but must cover all 9 of the shaded corner squares in 4 moves. An old chestnut in another guise.

You beat me to listing a similar one!

1. Q moves 2 squares straight down

2. diagonal 4 squares up and right

3. left sideways 4 squares to be above original starting place

4. diagonal 3 squares down and right to finish in the bottom right corner of the 9 - task complete!

[Sword]

[Sword]

It's much harder to do in your head!

Edited April 2, 2020 by Sword