出典:Wiktionary
出典:『Wiktionary』 (2026/05/21 21:26 UTC 版)
substitution instance (plural substitution instances)
Substitution instances are fundamental to the rules of universal instantiation and existential generalization. The notation Q(a/x) is read as "Q with a substituted for x." The term a must be free for x in Q, meaning that no free variable in a becomes bound by a quantifier in Q after substitution. e.g. If Q is the wff P(x) → ∃y R(x,y), then Q(c/x) is P(c) → ∃y R(c,y).