Pad 12:32 AM Files problems-mt1.pdf Find an equivalent DNF formula for the formula 2 (a) When are two formulas logically equivalear? Provide a definition (b) Are the following two formulas logically equivalent? Why A(B C) and (A B) C (c) Are the following two formulas logically equivalent? Why? A(B C) and B(AC) 3. Use the Quine's method to decide whether the following formula is a tautology, contingency or con- tradiction. (a) (A B) ((AVC) (BVC)) (b) (A V B) ((C VAJA (-C v B)) (a) Find a proof of the following tautology using the conditional proof rule 4. (B C) ((A ^ B) (A^ C)) (b) Find a proof of the following tautology using, among others, the indirect proof rule . Construct a proof for this statement: 6. (a) Transform this informal argument into a wff: No human beings are quadrupeds. All men are humans. Therefore, no man is a quadruped (b) Give a formal proof of this wff using either CP or IP 7. Use e's method to show that each of these wffs is a contingency 8 Use Quine's method to show that each of these wffs is a tautology