Tautology: Compound preposition which is always True.
i.e P∨P~=T
Contradiction: Compound preposition which is always False.
i.e.P∧P~=F
Contingency: Compound preposition which is sometimes True and sometimes False.
i.e.
P |
Q |
P ∧ Q |
T |
T |
T |
T |
F |
F |
F |
T |
F |
F |
F |
F |
Satisfiability: A Compound preposition is satisfiable if there is at least one True in its truth table.
So, Tautology is always satisfiable.
Unsatisfiability: Not even a single True result in its truth table.
FALLACIES :-A type of argument is a fallacy of propositional logic when two conditions are met: Itspropositional form is non-validating.
I hope this helps..