Theorem ncdisjeq 6149

Description: Two cardinals are either disjoint or equal. (Contributed by SF, 25-Feb-2015.)

Assertion

Ref	Expression
ncdisjeq	|- ((A e. NC /\ B e. NC ) -> ((A i^i B) = (/) \/ A = B))

Proof of Theorem ncdisjeq

Dummy variables x y are mutually distinct and distinct from all other variables.

Step	Hyp	Ref	Expression
1		elncs 6120	. . . 4 |- (A e. NC <-> E.x A = Nc x)
2		elncs 6120	. . . 4 |- (B e. NC <-> E.y B = Nc y)
3	1, 2	anbi12i 678	. . 3 |- ((A e. NC /\ B e. NC ) <-> (E.x A = Nc x /\ E.y B = Nc y))
4		eeanv 1913	. . 3 |- (E.xE.y(A = Nc x /\ B = Nc y) <-> (E.x A = Nc x /\ E.y B = Nc y))
5	3, 4	bitr4i 243	. 2 |- ((A e. NC /\ B e. NC ) <-> E.xE.y(A = Nc x /\ B = Nc y))
6		ener 6040	. . . . . 6 |- ~~ Er _V
7		erdisj 5973	. . . . . 6 |- ( ~~ Er _V -> ([x] ~~ = [y] ~~ \/ ([x] ~~ i^i [y] ~~ ) = (/)))
8	6, 7	ax-mp 5	. . . . 5 |- ([x] ~~ = [y] ~~ \/ ([x] ~~ i^i [y] ~~ ) = (/))
9		df-nc 6102	. . . . . . 7 |- Nc x = [x] ~~
10		eqtr 2370	. . . . . . 7 |- ((A = Nc x /\ Nc x = [x] ~~ ) -> A = [x] ~~ )
11	9, 10	mpan2 652	. . . . . 6 |- (A = Nc x -> A = [x] ~~ )
12		df-nc 6102	. . . . . . 7 |- Nc y = [y] ~~
13		eqtr 2370	. . . . . . 7 |- ((B = Nc y /\ Nc y = [y] ~~ ) -> B = [y] ~~ )
14	12, 13	mpan2 652	. . . . . 6 |- (B = Nc y -> B = [y] ~~ )
15		eqeq12 2365	. . . . . . 7 |- ((A = [x] ~~ /\ B = [y] ~~ ) -> (A = B <-> [x] ~~ = [y] ~~ ))
16		ineq12 3453	. . . . . . . 8 |- ((A = [x] ~~ /\ B = [y] ~~ ) -> (A i^i B) = ([x] ~~ i^i [y] ~~ ))
17	16	eqeq1d 2361	. . . . . . 7 |- ((A = [x] ~~ /\ B = [y] ~~ ) -> ((A i^i B) = (/) <-> ([x] ~~ i^i [y] ~~ ) = (/)))
18	15, 17	orbi12d 690	. . . . . 6 |- ((A = [x] ~~ /\ B = [y] ~~ ) -> ((A = B \/ (A i^i B) = (/)) <-> ([x] ~~ = [y] ~~ \/ ([x] ~~ i^i [y] ~~ ) = (/))))
19	11, 14, 18	syl2an 463	. . . . 5 |- ((A = Nc x /\ B = Nc y) -> ((A = B \/ (A i^i B) = (/)) <-> ([x] ~~ = [y] ~~ \/ ([x] ~~ i^i [y] ~~ ) = (/))))
20	8, 19	mpbiri 224	. . . 4 |- ((A = Nc x /\ B = Nc y) -> (A = B \/ (A i^i B) = (/)))
21	20	orcomd 377	. . 3 |- ((A = Nc x /\ B = Nc y) -> ((A i^i B) = (/) \/ A = B))
22	21	exlimivv 1635	. 2 |- (E.xE.y(A = Nc x /\ B = Nc y) -> ((A i^i B) = (/) \/ A = B))
23	5, 22	sylbi 187	1 |- ((A e. NC /\ B e. NC ) -> ((A i^i B) = (/) \/ A = B))

Syntax hints:   -> wi 4   <-> wb 176   \/ wo 357   /\ wa 358  E.wex 1541   = wceq 1642   e. wcel 1710  _Vcvv 2860   i^i cin 3209  (/)c0 3551   class class class wbr 4640   Er cer 5899  [cec 5946   ~~ cen 6029   NC cncs 6089   Nc cnc 6092

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-13 1712  ax-14 1714  ax-6 1729  ax-7 1734  ax-11 1746  ax-12 1925  ax-ext 2334  ax-nin 4079  ax-xp 4080  ax-cnv 4081  ax-1c 4082  ax-sset 4083  ax-si 4084  ax-ins2 4085  ax-ins3 4086  ax-typlower 4087  ax-sn 4088

This theorem depends on definitions:  df-bi 177  df-or 359  df-an 360  df-3or 935  df-3an 936  df-nan 1288  df-tru 1319  df-ex 1542  df-nf 1545  df-sb 1649  df-eu 2208  df-mo 2209  df-clab 2340  df-cleq 2346  df-clel 2349  df-nfc 2479  df-ne 2519  df-ral 2620  df-rex 2621  df-reu 2622  df-rmo 2623  df-rab 2624  df-v 2862  df-sbc 3048  df-nin 3212  df-compl 3213  df-in 3214  df-un 3215  df-dif 3216  df-symdif 3217  df-ss 3260  df-pss 3262  df-nul 3552  df-if 3664  df-pw 3725  df-sn 3742  df-pr 3743  df-uni 3893  df-int 3928  df-opk 4059  df-1c 4137  df-pw1 4138  df-uni1 4139  df-xpk 4186  df-cnvk 4187  df-ins2k 4188  df-ins3k 4189  df-imak 4190  df-cok 4191  df-p6 4192  df-sik 4193  df-ssetk 4194  df-imagek 4195  df-idk 4196  df-iota 4340  df-0c 4378  df-addc 4379  df-nnc 4380  df-fin 4381  df-lefin 4441  df-ltfin 4442  df-ncfin 4443  df-tfin 4444  df-evenfin 4445  df-oddfin 4446  df-sfin 4447  df-spfin 4448  df-phi 4566  df-op 4567  df-proj1 4568  df-proj2 4569  df-opab 4624  df-br 4641  df-1st 4724  df-swap 4725  df-sset 4726  df-co 4727  df-ima 4728  df-si 4729  df-id 4768  df-xp 4785  df-cnv 4786  df-rn 4787  df-dm 4788  df-res 4789  df-fun 4790  df-fn 4791  df-f 4792  df-f1 4793  df-fo 4794  df-f1o 4795  df-2nd 4798  df-txp 5737  df-ins2 5751  df-ins3 5753  df-image 5755  df-ins4 5757  df-si3 5759  df-funs 5761  df-fns 5763  df-trans 5900  df-sym 5909  df-er 5910  df-ec 5948  df-qs 5952  df-en 6030  df-ncs 6099  df-nc 6102

This theorem is referenced by:  nceleq  6150