Theorem difindiss 3485

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 3370	. . 3 |- ( x e. ( ( A \ B ) u. ( A \ C ) ) <-> ( x e. ( A \ B ) \/ x e. ( A \ C ) ) )
2		eldif 3229	. . . . . . 7 |- ( x e. ( A \ B ) <-> ( x e. A /\ -. x e. B ) )
3		eldif 3229	. . . . . . 7 |- ( x e. ( A \ C ) <-> ( x e. A /\ -. x e. C ) )
4	2, 3	orbi12i 776	. . . . . 6 |- ( ( x e. ( A \ B ) \/ x e. ( A \ C ) ) <-> ( ( x e. A /\ -. x e. B ) \/ ( x e. A /\ -. x e. C ) ) )
5		andi 830	. . . . . 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		pm3.14 765	. . . . . 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 3229	. . . . 5 |- ( x e. ( A \ ( B i^i C ) ) <-> ( x e. A /\ -. x e. ( B i^i C ) ) )
11		elin 3412	. . . . . . 7 |- ( x e. ( B i^i C ) <-> ( x e. B /\ x e. C ) )
12	11	notbii 678	. . . . . 6 |- ( -. x e. ( B i^i C ) <-> -. ( x e. B /\ x e. C ) )
13	12	anbi2i 461	. . . . 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 3252	1 |- ( ( A \ B ) u. ( A \ C ) ) C_ ( A \ ( B i^i C ) )

Syntax hints:   -. wn 3   /\ wa 104   \/ wo 720   e. wcel 2209   \ cdif 3217   u. cun 3218   i^i cin 3219   C_ wss 3220

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 623  ax-in2 624  ax-io 721  ax-5 1500  ax-7 1501  ax-gen 1502  ax-ie1 1546  ax-ie2 1547  ax-8 1557  ax-10 1558  ax-11 1559  ax-i12 1560  ax-bndl 1562  ax-4 1563  ax-17 1579  ax-i9 1583  ax-ial 1587  ax-i5r 1588  ax-ext 2220

This theorem depends on definitions:  df-bi 117  df-tru 1405  df-nf 1514  df-sb 1816  df-clab 2225  df-cleq 2231  df-clel 2234  df-nfc 2381  df-v 2823  df-dif 3222  df-un 3224  df-in 3226  df-ss 3233

This theorem is referenced by:  difdif2ss  3488  indmss  3490