Question

Checking logical equivalence of two different functions (or expressions). Why does my book say with n different variables there will be 2^n different assignments to check. I don't understand how that computation is valid.

Answer 1

Because of permutations in the truth value, i.e., if there are two variables, you have to check for:
1 1
0 0
1 0
0 1
which is 2^2 = 4. In the same manner, for every number of variables n, you have to check 2^n values.

Answer 2

Each variable has two possible values - True and False. Then for "n" variables you have 2^n assignments to check. In other words: That is all possible combinations of the variables with assigned value to them.

Answer 3

Alright. It's the number of end results required. I was on the assumption that they would be interested in # permutations but that assumption came from thin air. Thanks guys.

Answer 4

I'm not sure if "end results required" is what I mean. Evaluations to be compared perhaps.