Theorem ifpr 4233

Description: Membership of a conditional operator in an unordered pair. (Contributed by NM, 17-Jun-2007.)

Assertion

Ref	Expression
ifpr	|- ( ( A e. C /\ B e. D ) -> if ( ph , A , B ) e. { A , B } )

Proof of Theorem ifpr

Step	Hyp	Ref	Expression
1		elex 3212	. 2 |- ( A e. C -> A e. _V )
2		elex 3212	. 2 |- ( B e. D -> B e. _V )
3		ifcl 4130	. . 3 |- ( ( A e. _V /\ B e. _V ) -> if ( ph , A , B ) e. _V )
4		ifeqor 4132	. . . 4 |- ( if ( ph , A , B ) = A \/ if ( ph , A , B ) = B )
5		elprg 4196	. . . 4 |- ( if ( ph , A , B ) e. _V -> ( if ( ph , A , B ) e. { A , B } <-> ( if ( ph , A , B ) = A \/ if ( ph , A , B ) = B ) ) )
6	4, 5	mpbiri 248	. . 3 |- ( if ( ph , A , B ) e. _V -> if ( ph , A , B ) e. { A , B } )
7	3, 6	syl 17	. 2 |- ( ( A e. _V /\ B e. _V ) -> if ( ph , A , B ) e. { A , B } )
8	1, 2, 7	syl2an 494	1 |- ( ( A e. C /\ B e. D ) -> if ( ph , A , B ) e. { A , B } )

Syntax hints:   -> wi 4   \/ wo 383   /\ wa 384   = wceq 1483   e. wcel 1990   _Vcvv 3200   ifcif 4086   {cpr 4179

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-nfc 2753  df-v 3202  df-un 3579  df-if 4087  df-sn 4178  df-pr 4180

This theorem is referenced by:  suppr  8377  infpr  8409  uvcvvcl  20126  indf  30077