Theorem undi 1677

Description: Distributive law for union over intersection. Exercise 11 of [TakeutiZaring] p. 17.

Assertion

Ref	Expression
undi	|- (A u. (B i^i C)) = ((A u. B) i^i (A u. C))

Proof of Theorem undi

Step	Hyp	Ref	Expression
1		ordi 452	. . . 4 |- ((x e. A \/ (x e. B /\ x e. C)) <-> ((x e. A \/ x e. B) /\ (x e. A \/ x e. C)))
2		elin 1635	. . . . 5 |- (x e. (B i^i C) <-> (x e. B /\ x e. C))
3	2	orbi2i 214	. . . 4 |- ((x e. A \/ x e. (B i^i C)) <-> (x e. A \/ (x e. B /\ x e. C)))
4		elun 1601	. . . . 5 |- (x e. (A u. B) <-> (x e. A \/ x e. B))
5		elun 1601	. . . . 5 |- (x e. (A u. C) <-> (x e. A \/ x e. C))
6	4, 5	anbi12i 369	. . . 4 |- ((x e. (A u. B) /\ x e. (A u. C)) <-> ((x e. A \/ x e. B) /\ (x e. A \/ x e. C)))
7	1, 3, 6	3bitr4 158	. . 3 |- ((x e. A \/ x e. (B i^i C)) <-> (x e. (A u. B) /\ x e. (A u. C)))
8		elun 1601	. . 3 |- (x e. (A u. (B i^i C)) <-> (x e. A \/ x e. (B i^i C)))
9		elin 1635	. . 3 |- (x e. ((A u. B) i^i (A u. C)) <-> (x e. (A u. B) /\ x e. (A u. C)))
10	7, 8, 9	3bitr4 158	. 2 |- (x e. (A u. (B i^i C)) <-> x e. ((A u. B) i^i (A u. C)))
11	10	cleqri 1101	1 |- (A u. (B i^i C)) = ((A u. B) i^i (A u. C))

Syntax hints:   \/ wo 195   /\ wa 196   = wceq 1091   e. wcel 1092   u. cun 1485   i^i cin 1486

This theorem is referenced by:  undir 1679

This theorem was proved from axioms:  ax-1 3  ax-2 4  ax-3 5  ax-mp 6  ax-4 673  ax-5 674  ax-6 675  ax-7 676  ax-gen 677  ax-8 798  ax-9 799  ax-10 800  ax-11 801  ax-12 802  ax-16 922  ax-17 925  ax-ext 1074

This theorem depends on definitions:  df-bi 128  df-or 197  df-an 198  df-ex 679  df-sb 853  df-clab 1093  df-cleq 1097  df-clel 1099  df-v 1349  df-un 1490  df-in 1491

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