Theorem sbequ5 1665

Description: Substitution does not change an identical variable specifier. (Contributed by NM, 5-Aug-1993.) (Revised by NM, 21-Dec-2004.)

Assertion

Ref	Expression
sbequ5	|- ( [ w / z ] A. x x = y <-> A. x x = y )

Proof of Theorem sbequ5

Step	Hyp	Ref	Expression
1		nfae 1607	. 2 |- F/ z A. x x = y
2	1	sbf 1660	1 |- ( [ w / z ] A. x x = y <-> A. x x = y )

Syntax hints:   <-> wb 98   A.wal 1241   [wsb 1645

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 99  ax-ia2 100  ax-ia3 101  ax-io 630  ax-5 1336  ax-7 1337  ax-gen 1338  ax-ie1 1382  ax-ie2 1383  ax-8 1395  ax-10 1396  ax-11 1397  ax-i12 1398  ax-4 1400  ax-17 1419  ax-i9 1423  ax-ial 1427

This theorem depends on definitions:  df-bi 110  df-nf 1350  df-sb 1646

This theorem is referenced by: (None)