Theorem ifeq2da 3688

Description: Conditional equality. (Contributed by Jeff Madsen, 2-Sep-2009.)

Hypothesis

Ref	Expression
ifeq2da.1	|- ((ph /\ -. ps) -> A = B)

Assertion

Ref	Expression
ifeq2da	|- (ph -> if(ps, C, A) = if(ps, C, B))

Proof of Theorem ifeq2da

Step	Hyp	Ref	Expression
1		iftrue 3668	. . . 4 |- (ps -> if(ps, C, A) = C)
2		iftrue 3668	. . . 4 |- (ps -> if(ps, C, B) = C)
3	1, 2	eqtr4d 2388	. . 3 |- (ps -> if(ps, C, A) = if(ps, C, B))
4	3	adantl 452	. 2 |- ((ph /\ ps) -> if(ps, C, A) = if(ps, C, B))
5		ifeq2da.1	. . 3 |- ((ph /\ -. ps) -> A = B)
6	5	ifeq2d 3677	. 2 |- ((ph /\ -. ps) -> if(ps, C, A) = if(ps, C, B))
7	4, 6	pm2.61dan 766	1 |- (ph -> if(ps, C, A) = if(ps, C, B))

Syntax hints:  -. wn 3   -> wi 4   /\ wa 358   = wceq 1642  ifcif 3662

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1546  ax-5 1557  ax-17 1616  ax-9 1654  ax-8 1675  ax-6 1729  ax-7 1734  ax-11 1746  ax-12 1925  ax-ext 2334

This theorem depends on definitions:  df-bi 177  df-or 359  df-an 360  df-nan 1288  df-tru 1319  df-ex 1542  df-nf 1545  df-sb 1649  df-clab 2340  df-cleq 2346  df-clel 2349  df-nfc 2478  df-rab 2623  df-v 2861  df-nin 3211  df-compl 3212  df-un 3214  df-if 3663

This theorem is referenced by: (None)