(a) Show that the formula $$\left[ {\left( { \sim p \vee Q} \right) \Rightarrow \left( {q \Rightarrow p} \right)} \right]$$ is not a tautology.

(b) Let $$A$$ be a tautology and $$B$$ be any other formula. Prove that $$\left( {A \vee B} \right)$$ is a tautology.

The number of binary strings of $$n$$ zeros and $$k$$ ones such that no two ones are adjacent is:

Suppose that the expectation of a random variable X is 5. Which of the following statements is true?

Suppose that the expectation of a random variable X is 5. Which of the following statements is true?