Here are the 8 different logic rules that you should memorize the name or the abbreviations for. Equivalence rules Inference rules ----------------- --------------- dist (Distributive) mp (modus ponens) DM (De Morgan's) mt (modus tollens) contra (contrapositive) ds (disjunctive syllogism) imp (implication) dn (double negative) Without using any notes, using the letters P, Q and R, give the minimal number of numbered steps to illustrate each of the 3 inference rules, and give the minimum number of letters and logical operators to illustrate each of the 5 equivalence rules. 1. dist 2. mp 3. mt 4. DM 5. imp 6. dn 7. ds 8. contra Write down the 8 abbreviations on a separate sheet of paper, then write the name of the inference rule or the equivalence rule that each is an abbreviation or acronym for. Don't look at this sheet, or the exercise will not do you any good. For each of the inference rules, write the shortest possible proof involving A and B that proves B as the goal. Note that sometimes you will need to have A' or B' along with A, B and whatever operators are needed. 1. mt 2. mp 3. ds Now, go back an do each of the 3 different proofs using the other two rules instead of the rule you used. Each one will be longer, and you will have to bring in other rules, perhaps equivalence rules such as imp or contra, etc. For example, for the mt (modus tollens) proof from 1. mt above: Do 1. mt using mp instead of mt. Do 1. mt using ds instead of mt. For 2. mp proof you developed above: Do 2. mp using mt instead of mp. Do 2. mp using ds instead of mp. For 2. ds proof you developed above: Do 2. ds using mp instead of ds. Do 2. ds using mt instead of ds. ----------------------------------------------------------------------- If you can do this without looking at your notes or using the textbook and handouts, you are learning the rules and getting comfortable with the logical equivalence and logical inference rules and the required moves of the "game" of mathematical reasoning. ----------------------------------------------------------------------- 12. Prove that [ not (p and q) and q and (not r --> p) ] --> r a. How many premises or hyp will this proof have? b. What is the goal of the proof? c. Do the proof and number each step, as well as stating the reasons for each step and the justifications for each step, as we have always done in the classroom examples. 21. Simplify [ (A and B) or (A and C) ] and (not C) and (not B) (NOTE: The NOT operator has the highest precendence of all the operators, so writing not R ---> S means the same as (not R) ---> S and not S and not T means the same as (not S) and (not T) In other words, the parenthesis are NOT needed, because the not operator has a higher precedence than AND, OR and IMPLIES).