Theorem dmxpss 4343

Description: The domain of a cross product is a subclass of the first factor.

Assertion

Ref	Expression
dmxpss	|- dom ( A X. B) C_ A

Proof of Theorem dmxpss

Step	Hyp	Ref	Expression
1		0ss 2900	. . 3 |- (/) C_ A
2		xpeq2 4017	. . . . . . 7 |- (B = (/) -> (A X. B) = (A X. (/)))
3		xp0 4334	. . . . . . 7 |- (A X. (/)) = (/)
4	2, 3	syl6eq 1944	. . . . . 6 |- (B = (/) -> (A X. B) = (/))
5	4	dmeqd 4159	. . . . 5 |- (B = (/) -> dom ( A X. B) = dom (/))
6		dm0 4170	. . . . 5 |- dom (/) = (/)
7	5, 6	syl6eq 1944	. . . 4 |- (B = (/) -> dom ( A X. B) = (/))
8	7	sseq1d 2644	. . 3 |- (B = (/) -> (dom ( A X. B) C_ A <-> (/) C_ A))
9	1, 8	mpbiri 211	. 2 |- (B = (/) -> dom ( A X. B) C_ A)
10		dmxp 4177	. . 3 |- (B =/= (/) -> dom ( A X. B) = A)
11		eqimss 2665	. . 3 |- (dom ( A X. B) = A -> dom ( A X. B) C_ A)
12	10, 11	syl 12	. 2 |- (B =/= (/) -> dom ( A X. B) C_ A)
13	9, 12	pm2.61ine 2089	1 |- dom ( A X. B) C_ A

Syntax hints:   = wceq 1298   =/= wne 2017   C_ wss 2593  (/)c0 2875   X. cxp 3984  dom cdm 3986

This theorem is referenced by:  rnxpss 4344  ssxpb 4346  funssxp 4577  dff3 4790  fparlem3 5083  fparlem4 5084  brdom3 5963  brdom5 5964  brdom4 5965  dmrngcmp 15098

This theorem was proved from axioms:  ax-1 4  ax-2 5  ax-3 6  ax-mp 7  ax-7 1304  ax-gen 1305  ax-8 1306  ax-9 1307  ax-10 1308  ax-11 1309  ax-12 1310  ax-14 1312  ax-17 1317  ax-4 1319  ax-5o 1321  ax-6o 1324  ax-9o 1481  ax-10o 1500  ax-16 1580  ax-11o 1588  ax-ext 1865  ax-sep 3438  ax-nul 3445  ax-pow 3481  ax-pr 3524

This theorem depends on definitions:  df-bi 164  df-or 241  df-an 242  df-ex 1327  df-sb 1536  df-eu 1775  df-mo 1776  df-clab 1872  df-cleq 1877  df-clel 1880  df-ne 2019  df-ral 2109  df-v 2294  df-dif 2597  df-un 2600  df-in 2603  df-ss 2605  df-nul 2876  df-pw 3035  df-sn 3049  df-pr 3050  df-op 3053  df-br 3339  df-opab 3396  df-xp 4000  df-rel 4001  df-cnv 4002  df-dm 4004

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