converse
if q then p
inverse
if not p then not q
contrapositive (equivalent to if p then q)
If not q, then not p
negation
p and not q
equivalent
not p or q
A?B
A
... B
valid
A?B
~B
... ~A
valid
A?B
B?C
... A?C
valid
A or B
~A
... B
valid
A or B
~B
... A
valid
A?B
B
... A
invalid
A?B
~A
... ~B
invalid
A?B
A?C
... B?C
invalid
A?B
C?B
... A?C
invalid
A or B
A
... ~B
invalid
A or B
B
... ~A
invalid