Theorem ifan 4134

Description: Rewrite a conjunction in an if statement as two nested conditionals. (Contributed by Mario Carneiro, 28-Jul-2014.)

Assertion

Ref	Expression
ifan	|- if ( ( ph /\ ps ) , A , B ) = if ( ph , if ( ps , A , B ) , B )

Proof of Theorem ifan

Step	Hyp	Ref	Expression
1		iftrue 4092	. . 3 |- ( ph -> if ( ph , if ( ps , A , B ) , B ) = if ( ps , A , B ) )
2		ibar 525	. . . 4 |- ( ph -> ( ps <-> ( ph /\ ps ) ) )
3	2	ifbid 4108	. . 3 |- ( ph -> if ( ps , A , B ) = if ( ( ph /\ ps ) , A , B ) )
4	1, 3	eqtr2d 2657	. 2 |- ( ph -> if ( ( ph /\ ps ) , A , B ) = if ( ph , if ( ps , A , B ) , B ) )
5		simpl 473	. . . . 5 |- ( ( ph /\ ps ) -> ph )
6	5	con3i 150	. . . 4 |- ( -. ph -> -. ( ph /\ ps ) )
7	6	iffalsed 4097	. . 3 |- ( -. ph -> if ( ( ph /\ ps ) , A , B ) = B )
8		iffalse 4095	. . 3 |- ( -. ph -> if ( ph , if ( ps , A , B ) , B ) = B )
9	7, 8	eqtr4d 2659	. 2 |- ( -. ph -> if ( ( ph /\ ps ) , A , B ) = if ( ph , if ( ps , A , B ) , B ) )
10	4, 9	pm2.61i 176	1 |- if ( ( ph /\ ps ) , A , B ) = if ( ph , if ( ps , A , B ) , B )

Syntax hints:   -. wn 3   /\ wa 384   = wceq 1483   ifcif 4086

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-if 4087

This theorem is referenced by:  itg0  23546  iblre  23560  itgreval  23563  iblss  23571  iblss2  23572  itgle  23576  itgss  23578  itgeqa  23580  iblconst  23584  itgconst  23585  ibladdlem  23586  iblabslem  23594  iblabsr  23596  iblmulc2  23597  itgsplit  23602  itgcn  23609  mrsubrn  31410  itg2gt0cn  33465  ibladdnclem  33466  iblabsnclem  33473  iblmulc2nc  33475  bddiblnc  33480  iblsplit  40182