The aim is for A and B to guess the right card from the below deck of cards.
A is told the number only of the card.
B is told the shape only of the card.
Based on the following conversation between A and B, A and B manage to guess correctly the right card.
A: I don't know the card.
B: Before you mentioned, I already know you don't know, but I still don't know.
A: Now, I know the card.
B: I also know the card now.
Ok so my question is: Why is the answer 5 diamond? It could also be Queen-heart and 4-heart.
From 1, the message from A provides me the information that the right card has at least 1 other card with the same number though different symbol. As such, I can already rule out those cards without at least 1 other card with the same number.
From 2, the message from B provides me and A some information about the symbol of the right card. I can already rule out ALL spade and club because 8 spade and 6 club do not have at least one other card of the same number but different symbol.
From 3, the message from A provides me and B information that Ace heart and Ace diamond can be ruled out because after A received B's message from Line 2, A can decisively know the answer.
Now here lies the confusion for me -- hope some kind soul can enlighten me -- how could B reply "I also know the card" and choose 5 diamond because, at least to me, there is not enough information for B to conclude logically that it is 5 diamond.
It could also be Queen-heart and 4-heart.
Yep thanks @JosephCamacho for pointing out my confusion.
From 4, the message from B provides me the information about the right card is 5 diamond because B can decisively make a choice. Supposed if the right card is queen-heart and 4-heart, B cannot make the statement that "I also know the card now" because he will be stuck between queen-heart and 4-heart.
Ahhh can't believe I got stuck at this simple logic -.-"