Theorem eqsbc3rOLD 3493

Description: Obsolete proof of eqsbc3r 3492 as of 7-Jul-2021. This proof was automatically generated from the virtual deduction proof eqsbc3rVD 39075 using a translation program. (Contributed by Alan Sare, 24-Oct-2011.) (New usage is discouraged.) (Proof modification is discouraged.)

Assertion

Ref	Expression
eqsbc3rOLD	|- ( A e. V -> ( [. A / x ]. B = x <-> B = A ) )

Distinct variable group:   x, B

Allowed substitution hints:   A( x)   V( x)

Proof of Theorem eqsbc3rOLD

Step	Hyp	Ref	Expression
1		eqcom 2629	. . . . . 6 |- ( B = x <-> x = B )
2	1	sbcbii 3491	. . . . 5 |- ( [. A / x ]. B = x <-> [. A / x ]. x = B )
3	2	biimpi 206	. . . 4 |- ( [. A / x ]. B = x -> [. A / x ]. x = B )
4		eqsbc3 3475	. . . 4 |- ( A e. V -> ( [. A / x ]. x = B <-> A = B ) )
5	3, 4	syl5ib 234	. . 3 |- ( A e. V -> ( [. A / x ]. B = x -> A = B ) )
6		eqcom 2629	. . 3 |- ( A = B <-> B = A )
7	5, 6	syl6ib 241	. 2 |- ( A e. V -> ( [. A / x ]. B = x -> B = A ) )
8		idd 24	. . . . 5 |- ( A e. V -> ( B = A -> B = A ) )
9	8, 6	syl6ibr 242	. . . 4 |- ( A e. V -> ( B = A -> A = B ) )
10	9, 4	sylibrd 249	. . 3 |- ( A e. V -> ( B = A -> [. A / x ]. x = B ) )
11	10, 2	syl6ibr 242	. 2 |- ( A e. V -> ( B = A -> [. A / x ]. B = x ) )
12	7, 11	impbid 202	1 |- ( A e. V -> ( [. A / x ]. B = x <-> B = A ) )

Syntax hints:   -> wi 4   <-> wb 196   = wceq 1483   e. wcel 1990   [.wsbc 3435

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1722  ax-4 1737  ax-5 1839  ax-6 1888  ax-7 1935  ax-9 1999  ax-10 2019  ax-11 2034  ax-12 2047  ax-13 2246  ax-ext 2602

This theorem depends on definitions:  df-bi 197  df-or 385  df-an 386  df-tru 1486  df-ex 1705  df-nf 1710  df-sb 1881  df-clab 2609  df-cleq 2615  df-clel 2618  df-v 3202  df-sbc 3436

This theorem is referenced by: (None)