>>12337176p = it rains
q = the earth is wet
p=0,q=0: it didn't rain, the earth isn't wet
p=0,q=1: it didn't rain, but the earth is wet
p=1,q=0: it did rain, but the earth isn't wet
p=1, q=1: it did rain, the earth is wet
All but the third are logically valid.
