Inference patterns
(Trans) Transitivity
p □→ q, q □→ r, therefore p □→ r
(Contr) Contraposability
p □→ q, therefore ~q □→ ~p
(Stren) Strengthening
p □→ q, therefore (p & r) □→ q
(Trans) Transitivity
p □→ q, q □→ r, therefore p □→ r
(Contr) Contraposability
p □→ q, therefore ~q □→ ~p
(Stren) Strengthening
p □→ q, therefore (p & r) □→ q