math
posted by bill .
In the bac of an old cupboard you discover a note signed by a pirate famous for his bizarre sense of humor and love of logical puzzles. In the note he wrote that he had hidden treasure somewhere on the property. He listed five true statements and challenged the reader to use them to figure out the location of the tresure. Where is the treasure hidden?
1. if this house is next to the lake, than the treasure is not in the kitchen
2. if the tree in the front yard is an elm, then the treasure is in the kitchen
3. This house is next to the lake
4. the tree in the front yard is an elm of the treasure is buried under the flagpole
5. if the tree in the backyard is an oak, then the treasure is in the garage.

3. Therefore, using 1, treasure not in kitchen.
2. tree is not elm, since treasure not in kitchen.
not 4, so 5. treasure is in garage. 
Actually, all we know is that the tree is not an elm. We have no indication it is an oak. What if it's a maple or a pine?
So, really, we don't know where the treasure is. We just know it's not in the kitchen or under the flagpole.