Let $$p$$ and $$q$$ be propositions. Using only the truth table decide whether $$p \Leftrightarrow q$$ does not imply $$p \to \sim q$$ is true or false.

Let A and B be any two arbitrary events, then, which one of the following is true?

Some group (G, o) is known to be abelian. Then, which one of the following is true for G?

The number of substrings (of all length inclusive) that can be formed from a character string of length $$n$$ is