Solution to "x implies y" Part I: Answer: Yes. Solution: White Triangle is "frobby" Therefore the shape that is being thought of is either Black Triangle or White Circle.  For both of these, the other "frobby" shape is the Black Circle. Part II: Answer: 2; card 5 and card F Solution: The key to this solution is to read the question carefully, especially this sentance: "a card with an odd number on one side must have a vowel on the other" There are no other rules! No rule that cards with vowels on one side must have odd numbers on the other side, no rule that cards with even numbers must have consonants, etc, etc ... Going through the 4 cards: Card "2" : must not be turned.  As this card does not have an odd number on one side, we do not care what letter is on the other side. Card "5": Must check that the other side is a vowel to prove the rule. Card "F": Must check that the other side is NOT an odd number - if it is then the rule would be proved false. Card "E": This is a vowel, therefore it deosnt matter whether or not the other side is odd. C.Speirs Tuesday, January 4, 2005   Fog Creek Home