00:01
For this problem, we'd like to see whether or not the proposition given below is a contradiction.
00:11
So let's go ahead and just make a true table.
00:14
And if the final column, which will be this, is always false, that's what it means to be a contradiction.
00:23
So p could be either true or false because p is just an arbitrary proposition.
00:28
We also see not p here.
00:30
So let's go ahead and negate column one.
00:34
Okay, here i see p or not p.
00:40
So if either one of them is true, that makes the column 3, which is the or, and finally, the one of interest here, not p, if and only if, p or not p.
01:01
Now, here's a fact that we want to recall here...