Statements :No letter is a fax.All messages are faxes.Conclusions :I. No message is a letter.II. At least some faxes are messages.
if only conclusion I follows.
if only conclusion II follows.
if either conclusion I or II follows.
Statements: P $ Q, Q δ S, S * R
Conclusions:
I. S * P
II. S $ P
Statements: Y © S, S δ R, R * Q Conclusions: I. Q @ S II. Y * R
Statements: W δ U, U @ G, G $ M
I. M * U
II. G * W