2.10. Use a truth table to prove that the implication A B and its converse B- A are not logically equivalent. 2.11. Show that (A ? B) ? (B ? A) and A?B are logically equivalent 2.12. Show that (A ^ (A ? B)) ? B is a tautology. This is the basis for the modus ponens inference rule: If A and A ? L3 are Irue, then we can conclude that B must be true