X Implies Y Part 1 : It's actually rather neat.  If a White Triangle is frobby, then either the "White" or the "Triangle" makes it Frobby. That makes "Black Triangle" or the "White Circle" unfrobby, because it has BOTH qualifications.  Now, if the "White" and "Circle" are the qualifications, then the "Black" "Triangle" is unfrobby, because it has none of the qualifications.  Vice versa. White Triangle = Frobby Black Triangle = UnFrobby White Circle = UnFrobby and that makes the Black Circle = Frobby For the Part 2, you need to turn over the 5 and the F. You don't need to turn over the 2, because there is no rule about what might or might not be on the other side of even numbers. You need to turn over the 5, because there might be a consonant on the other side. You need to turn over the F, because there might be an odd number on the other side.  You don't need to turn over the E, because there's no rule that says an Vowels can only be on the flip side of odd numbers. Fred Garber Monday, July 29, 2002   Fog Creek Home