Theorem stdpc6 1702

Description: One of the two equality axioms of standard predicate calculus, called reflexivity of equality. (The other one is stdpc7 1946.) Axiom 6 of [Mendelson] p. 95. Mendelson doesn't say why he prepended the redundant quantifier, but it was probably to be compatible with free logic (which is valid in the empty domain). (Contributed by NM, 16-Feb-2005.)

Assertion

Ref	Expression
stdpc6

Proof of Theorem stdpc6

Step	Hyp	Ref	Expression
1		equid 1691	. 2
2	1	ax-gen 1556	1

Syntax hints:  A.wal 1550

This theorem is referenced by:  cbv3hOLD  1981  cbv3hOLD7  29965

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1556  ax-5 1567  ax-17 1628  ax-9 1669  ax-8 1690

This theorem depends on definitions:  df-bi 179  df-ex 1552