Theorem sbccom 3118

Description: Commutative law for double class substitution. (Contributed by NM, 15-Nov-2005.) (Proof shortened by Mario Carneiro, 18-Oct-2016.)

Assertion

Ref	Expression
sbccom	|- ( [.A / x ]. [.B / y ].ph <-> [.B / y ]. [.A / x ].ph)

Distinct variable groups:   y,A   x,B   x,y

Allowed substitution hints:   ph(x,y)   A(x)   B(y)

Proof of Theorem sbccom

Dummy variables w z are mutually distinct and distinct from all other variables.

Step	Hyp	Ref	Expression
1		sbccomlem 3117	. . . 4 |- ( [.A / z ]. [.B / w ]. [.w / y ]. [.z / x ].ph <-> [.B / w ]. [.A / z ]. [.w / y ]. [.z / x ].ph)
2		sbccomlem 3117	. . . . . . 7 |- ( [.w / y ]. [.z / x ].ph <-> [.z / x ]. [.w / y ].ph)
3	2	sbcbii 3102	. . . . . 6 |- ( [.B / w ]. [.w / y ]. [.z / x ].ph <-> [.B / w ]. [.z / x ]. [.w / y ].ph)
4		sbccomlem 3117	. . . . . 6 |- ( [.B / w ]. [.z / x ]. [.w / y ].ph <-> [.z / x ]. [.B / w ]. [.w / y ].ph)
5	3, 4	bitri 240	. . . . 5 |- ( [.B / w ]. [.w / y ]. [.z / x ].ph <-> [.z / x ]. [.B / w ]. [.w / y ].ph)
6	5	sbcbii 3102	. . . 4 |- ( [.A / z ]. [.B / w ]. [.w / y ]. [.z / x ].ph <-> [.A / z ]. [.z / x ]. [.B / w ]. [.w / y ].ph)
7		sbccomlem 3117	. . . . 5 |- ( [.A / z ]. [.w / y ]. [.z / x ].ph <-> [.w / y ]. [.A / z ]. [.z / x ].ph)
8	7	sbcbii 3102	. . . 4 |- ( [.B / w ]. [.A / z ]. [.w / y ]. [.z / x ].ph <-> [.B / w ]. [.w / y ]. [.A / z ]. [.z / x ].ph)
9	1, 6, 8	3bitr3i 266	. . 3 |- ( [.A / z ]. [.z / x ]. [.B / w ]. [.w / y ].ph <-> [.B / w ]. [.w / y ]. [.A / z ]. [.z / x ].ph)
10		sbcco 3069	. . 3 |- ( [.A / z ]. [.z / x ]. [.B / w ]. [.w / y ].ph <-> [.A / x ]. [.B / w ]. [.w / y ].ph)
11		sbcco 3069	. . 3 |- ( [.B / w ]. [.w / y ]. [.A / z ]. [.z / x ].ph <-> [.B / y ]. [.A / z ]. [.z / x ].ph)
12	9, 10, 11	3bitr3i 266	. 2 |- ( [.A / x ]. [.B / w ]. [.w / y ].ph <-> [.B / y ]. [.A / z ]. [.z / x ].ph)
13		sbcco 3069	. . 3 |- ( [.B / w ]. [.w / y ].ph <-> [.B / y ].ph)
14	13	sbcbii 3102	. 2 |- ( [.A / x ]. [.B / w ]. [.w / y ].ph <-> [.A / x ]. [.B / y ].ph)
15		sbcco 3069	. . 3 |- ( [.A / z ]. [.z / x ].ph <-> [.A / x ].ph)
16	15	sbcbii 3102	. 2 |- ( [.B / y ]. [.A / z ]. [.z / x ].ph <-> [.B / y ]. [.A / x ].ph)
17	12, 14, 16	3bitr3i 266	1 |- ( [.A / x ]. [.B / y ].ph <-> [.B / y ]. [.A / x ].ph)

Syntax hints:   <-> wb 176   [.wsbc 3047

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-tru 1319  df-ex 1542  df-nf 1545  df-sb 1649  df-clab 2340  df-cleq 2346  df-clel 2349  df-nfc 2479  df-v 2862  df-sbc 3048

This theorem is referenced by:  csbcomg  3160  csbabg  3198  cnvopab  5031  eqerlem  5961