Theorem sb6a 2192

Description: Equivalence for substitution. (Contributed by NM, 2-Jun-1993.) (Proof shortened by Wolf Lammen, 23-Sep-2018.)

Assertion

Ref	Expression
sb6a

Distinct variable group:   ,

Proof of Theorem sb6a

Step	Hyp	Ref	Expression
1		sbco 2154	. 2
2		sb6 2173	. 2
3	1, 2	bitr3i 251	1

Syntax hints:  ->wi 4  <->wb 184  A.wal 1393  [wsb 1739

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1618  ax-4 1631  ax-5 1704  ax-6 1747  ax-7 1790  ax-10 1837  ax-12 1854  ax-13 1999

This theorem depends on definitions:  df-bi 185  df-or 370  df-an 371  df-ex 1613  df-nf 1617  df-sb 1740