INSTRUCTIONS: This assignment is due January 29th 1999, in class. Groups may hand in a single assignment paper. The maximum group size is 4.
The assignments must have the name and York number of all group members listed at the top of the paper.
So since is T (or true) in all states, it is a tautology.
By Metatheorem which says if since and we have .
By TRANSITIVITY 4 times and hence by EQUANIMITY .
Now , and by TRASITIVITY 3 times, and so by EQUANIMITY.