00:01
For this problem, we wish to show that the statement not p implies q implies r is the same as the statement q implies p or r, and we will do so using a truth table.
00:16
Now i've already constructed a truth table that evaluates all possible truth values for the three statements p, q, and r.
00:25
I've also filled in the column for the negation not p.
00:29
This gives us eight instances in which we need to evaluate each of the following statements.
00:34
First, let's look at q implies r.
00:38
Now an implication statement is only false when we have a true statement implying a false statement, which happens in this row.
00:48
True implies false, and this row we have true implies false.
00:55
It seems that in every other row, the implication statement will be true.
01:00
So we can proceed with true, false, we have true, true, true, false, true.
01:11
And now we use this column to evaluate not p implies q implies r.
01:16
Same thing here, we're going to look for state cases where not p is true, but q implies r is false, which that happens right here, and it doesn't look like it happens anywhere else.
01:30
So we're going to have true, true, true, true, true, false, true, true.
01:38
And that concludes this column...