Theorem a16gb 1876

Description: A generalization of Axiom ax-16 1825. (Contributed by NM, 5-Aug-1993.)

Assertion

Ref	Expression
a16gb	|- ( A. x x = y -> ( ph <-> A. z ph ) )

Distinct variable group:   x, y

Allowed substitution hints:   ph( x, y, z)

Proof of Theorem a16gb

Step	Hyp	Ref	Expression
1		a16g 1875	. 2 |- ( A. x x = y -> ( ph -> A. z ph ) )
2		ax-4 1521	. 2 |- ( A. z ph -> ph )
3	1, 2	impbid1 142	1 |- ( A. x x = y -> ( ph <-> A. z ph ) )

Syntax hints:   -> wi 4   <-> wb 105   A.wal 1362

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-io 710  ax-5 1458  ax-7 1459  ax-gen 1460  ax-ie1 1504  ax-ie2 1505  ax-8 1515  ax-10 1516  ax-11 1517  ax-i12 1518  ax-4 1521  ax-17 1537  ax-i9 1541  ax-ial 1545

This theorem depends on definitions:  df-bi 117  df-nf 1472  df-sb 1774

This theorem is referenced by: (None)