All men are Athenians. Some Athenians are mortal. Some men are mortal. All Athenians are men. Some Athenians are mortal.
Some men are mortal.
All men are Athenians. Some mortals are Athenian. Show using truth tables that the following pairs of sentences are equivalent. Assume that you are told truthfully that the number is not even and that it is neither 1 nor 3. You reason that it must be 5.