Axiom ax-10 966

Description: Axiom of Quantifier Substitution. One of the equality and substitution axioms of predicate calculus with equality. Appears as Lemma L12 in [Megill] p. 445 (p. 12 of the preprint).

This axiom replaces the old axiom ax-10o 1140, which is proved from this one as theorem ax10o 1139. Conversely, this axiom is proved from ax-10o 1140 as theorem ax10 1141.

Assertion

Ref	Expression
ax-10	|- (A.x x = y -> A.y y = x)

Detailed syntax breakdown of Axiom ax-10

Step	Hyp	Ref	Expression
1		vx	. . . . 5 set x
2	1	cv 955	. . . 4 class x
3		vy	. . . . 5 set y
4	3	cv 955	. . . 4 class y
5	2, 4	wceq 956	. . 3 wff x = y
6	5, 1	wal 954	. 2 wff A.x x = y
7	4, 2	wceq 956	. . 3 wff y = x
8	7, 3	wal 954	. 2 wff A.y y = x
9	6, 8	wi 3	1 wff (A.x x = y -> A.y y = x)

This axiom is referenced by:  ax10o 1139  alequcom 1142

Copyright terms: Public domain