Theorem difindiss 3417

Description: Distributive law for class difference. In classical logic, for example, theorem 40 of [Suppes] p. 29, this is an equality instead of subset. (Contributed by Jim Kingdon, 26-Jul-2018.)

Assertion

Ref	Expression
difindiss	|- ( ( A \ B ) u. ( A \ C ) ) C_ ( A \ ( B i^i C ) )

Proof of Theorem difindiss

Dummy variable x is distinct from all other variables.

Step	Hyp	Ref	Expression
1		elun 3304	. . 3 |- ( x e. ( ( A \ B ) u. ( A \ C ) ) <-> ( x e. ( A \ B ) \/ x e. ( A \ C ) ) )
2		eldif 3166	. . . . . . 7 |- ( x e. ( A \ B ) <-> ( x e. A /\ -. x e. B ) )
3		eldif 3166	. . . . . . 7 |- ( x e. ( A \ C ) <-> ( x e. A /\ -. x e. C ) )
4	2, 3	orbi12i 765	. . . . . 6 |- ( ( x e. ( A \ B ) \/ x e. ( A \ C ) ) <-> ( ( x e. A /\ -. x e. B ) \/ ( x e. A /\ -. x e. C ) ) )
5		andi 819	. . . . . 6 |- ( ( x e. A /\ ( -. x e. B \/ -. x e. C ) ) <-> ( ( x e. A /\ -. x e. B ) \/ ( x e. A /\ -. x e. C ) ) )
6	4, 5	bitr4i 187	. . . . 5 |- ( ( x e. ( A \ B ) \/ x e. ( A \ C ) ) <-> ( x e. A /\ ( -. x e. B \/ -. x e. C ) ) )
7		pm3.14 754	. . . . . 6 |- ( ( -. x e. B \/ -. x e. C ) -> -. ( x e. B /\ x e. C ) )
8	7	anim2i 342	. . . . 5 |- ( ( x e. A /\ ( -. x e. B \/ -. x e. C ) ) -> ( x e. A /\ -. ( x e. B /\ x e. C ) ) )
9	6, 8	sylbi 121	. . . 4 |- ( ( x e. ( A \ B ) \/ x e. ( A \ C ) ) -> ( x e. A /\ -. ( x e. B /\ x e. C ) ) )
10		eldif 3166	. . . . 5 |- ( x e. ( A \ ( B i^i C ) ) <-> ( x e. A /\ -. x e. ( B i^i C ) ) )
11		elin 3346	. . . . . . 7 |- ( x e. ( B i^i C ) <-> ( x e. B /\ x e. C ) )
12	11	notbii 669	. . . . . 6 |- ( -. x e. ( B i^i C ) <-> -. ( x e. B /\ x e. C ) )
13	12	anbi2i 457	. . . . 5 |- ( ( x e. A /\ -. x e. ( B i^i C ) ) <-> ( x e. A /\ -. ( x e. B /\ x e. C ) ) )
14	10, 13	bitr2i 185	. . . 4 |- ( ( x e. A /\ -. ( x e. B /\ x e. C ) ) <-> x e. ( A \ ( B i^i C ) ) )
15	9, 14	sylib 122	. . 3 |- ( ( x e. ( A \ B ) \/ x e. ( A \ C ) ) -> x e. ( A \ ( B i^i C ) ) )
16	1, 15	sylbi 121	. 2 |- ( x e. ( ( A \ B ) u. ( A \ C ) ) -> x e. ( A \ ( B i^i C ) ) )
17	16	ssriv 3187	1 |- ( ( A \ B ) u. ( A \ C ) ) C_ ( A \ ( B i^i C ) )

Syntax hints:   -. wn 3   /\ wa 104   \/ wo 709   e. wcel 2167   \ cdif 3154   u. cun 3155   i^i cin 3156   C_ wss 3157

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-in1 615  ax-in2 616  ax-io 710  ax-5 1461  ax-7 1462  ax-gen 1463  ax-ie1 1507  ax-ie2 1508  ax-8 1518  ax-10 1519  ax-11 1520  ax-i12 1521  ax-bndl 1523  ax-4 1524  ax-17 1540  ax-i9 1544  ax-ial 1548  ax-i5r 1549  ax-ext 2178

This theorem depends on definitions:  df-bi 117  df-tru 1367  df-nf 1475  df-sb 1777  df-clab 2183  df-cleq 2189  df-clel 2192  df-nfc 2328  df-v 2765  df-dif 3159  df-un 3161  df-in 3163  df-ss 3170

This theorem is referenced by:  difdif2ss  3420  indmss  3422