Learn the four rules ~, v, •, > 1. ~ means the opposite of what follows the ~ 2. FvF is the only false case of v, all others T. 3. T•T is the only true case of •, all others F. 4. T>F is the only false case of >, all others T. Write the expression across the paper. Under the K's put TTTTFFFF Under the P's put TTFFTTFF Under the R's put TFTFTFTF [K • (P v ~ R)] • [K > (R • ~ P)] T T T T T T T T F T F T T F T T T F T F F T F F F T T F T T F T F F F T F F T F T F F F F F F F Under the ~'s, put F if ~ is before a T and F if ~ is before a T [K • (P v ~ R)] • [K > (R • ~ P)] T T F T T T F T T T T F T F F T T F F T T T T F T F T F T F T F F T F T F T F T F T T F F F F T F F F T F T T F F F T F F F T F Erase the T's and F's in the columns you just use to get the last columns you put in. [K • (P v ~ R)] • [K > (R • ~ P)] T T F T T F T T T T F F T F F T T T T F T T F T F T F F T F F T T F F F F F F F T T F F T F F T Staying within the first innermost parentheses (), under the v, put T everywhere except where v is between two F's. This is the only time we put F. [You will notice that this his rule is the exact opposite of what we will put under •]. [K • (P v ~ R)] • [K > (R • ~ P)] T T T F T T F T T T T T F F T F F F T T T T F T T T F T F T T F F T F F T T T F F F F F F F F T T F F T T F F T Erase the two columns of T's and F's that we used to get the last column we made: [K • (P v ~ R)] • [K > (R • ~ P)] T T T T F T T T F F T F T T T T T T F T F T F T F F T F F F F F F T T F T F F T Staying within the other innermost parentheses, () under the •, put F everywhere except where • is between two T's. This is the only time we put T. [This rule is the exact opposite of what we put under v]. [K • (P v ~ R)] • [K > (R • ~ P)] T T T T F F T T T F F F T F T T T T T T T F F T F T F T F F F T F F F F F F F T T T F T F F F T Erase the two columns of T's and F's that we used to get the last column we made: [K • (P v ~ R)] • [K > (R • ~ P)] T T T F T T T F T F T T T T T F F T F F F T F F F F F T F T F F Staying within the first innermost brackets, [], under the •, as before, put F everywhere except where • is between two T's. This is the only time we put T. [K • (P v ~ R)] • [K > (R • ~ P)] T T T T F T T T T F T F F T T T T T T F F F T F F F F T F F F F F F T F F T F F Erase the two columns of T's and F's that we used to get the last column we made: [K • (P v ~ R)] • [K > (R • ~ P)] T T F T T F F T T T T F F F F F F F F F T F F F Staying within the other innermost brackets, [], under the >, put T everywhere except where > has T on the left and F on the right. This is the only time we put T. [K • (P v ~ R)] • [K > (R • ~ P)] T T F F T T F F F T T T T T F F F F T F F F T F F F T T F F T F Erase the two columns of T's and F's that we used to get the last column we made: [K • (P v ~ R)] • [K > (R • ~ P)] T F T F F T T F F T F T F T F T Now that we have finished all the parentheses and brackets, we are dow to just 2 columns of T's and F's. Under the final • outside all parentheses and brackets we put F's for everything but T•T. There are none, so we put F's for everything. [K • (P v ~ R)] • [K > (R • ~ P)] T F F T F F F F T T F F F F T F F T F F T F F T We erase the two columns of T's and F's that we used to get the last column we made: [K • (P v ~ R)] • [K > (R • ~ P)] F F F F F F F F Since all the values are F, the statement is a logical contradiction, which means it is always false. [In other problems, when all the values are T, the statement is a logical tautology, or always true.] [In other problems when some are T and some are F, the statement is a contingency, or sometimes true and sometimes false.] Edwin