============================================================================= notation: '==' is logical equivalence; '->' is implication; '^' is AND; 'v' is OR; '~' is NOT; '<->' is biconditional; XOR is exclusive or Precedence Order (highest to lowest): () NOT AND OR -> <-> ============================================================================= identity laws p ^ T == p p v F == p ----------------------------------------------------------------------------- domination laws p v T = T p ^ F = F ----------------------------------------------------------------------------- negation laws p v ~p == T p ^ ~p == F ----------------------------------------------------------------------------- idempotent laws p v p == p p ^ p == p ----------------------------------------------------------------------------- commutativity (p ^ q) == (q ^ p) (p v q) == (q v p) ------------------------------------------------------------------------------ associativity (p ^ q) ^ r == p ^ (q ^ r) (p v q) v r == p v (q v r) ------------------------------------------------------------------------------ double negation elimination ~(~p) == p ------------------------------------------------------------------------------ contraposition p -> q == ~q -> ~p ------------------------------------------------------------------------------ implication elimination p -> q == ~p v q ------------------------------------------------------------------------------- biconditional elimination p <-> q == (p -> q) ^ (q -> p) ------------------------------------------------------------------------------- De Morgan ~( p ^ q) == ~p v ~q ~( p v q) == ~p ^ ~ q ------------------------------------------------------------------------------- distributivity of ^ over v and v over ^ p ^ (q v r) == (p ^ q) v ( p ^ r) p v (q ^ r) == (p v q) ^ (p v r) ------------------------------------------------------------------------------- absorption p v (p ^ q ) == p p ^ (p v q) == p ------------------------------------------------------------------------------- Rules of Inference for Propositional and Predicate Logic ':' is therefore; 'v' is "OR"; '~' is NOT; '^' is AND; '->' is implication ------------------------------------------------------------------------------- p q Conjunction (Conj.) ----------- : p ^ q p -> q Modus Ponens (M.P.) p ---------- : q p -> q Modus Tollens (M.T.) ~q ---------- : ~p p -> q Hypothetical Syllogism (H.S.) q -> r ---------- : p -> r p v q Disjunctive Syllogism (D.S.) ~ p ---------- : q (p -> q) ^ (r -> s) Constructive Dilemma (C.D.) p v r --------------------- : q v s p -> q Absorption (Abs.) --------------- : p -> (p ^ q) p ^ q Simplification (Simp.) ----------- : p p Addition (Add.) ----------- : p v q p v q Resolution (Res.) ~p v r ----------- : q v r Fallacy of affirming the consequence (or conclusion) p -> q q ------- p Fallacy of denying the antecedent (or hypothesis) p -> q ~p ------- ~q Rules of Inference for Quantified Statements ------------------------------------------------------------------------------- Given Universe of Discourse = U and c member of U Universal Instantiation Ax P(x) ----------- : P(c) for some element c Universal Generalization P(c) for an arbitrary c ---------- : Ax P(x) Existential Instantiation Ex P(x) ----------- : P(c) for some element c Existential Generalization P(c) for an arbitrary c ---------- : Ex P(x)