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Theorem xpcomen 8996

Description: Commutative law for equinumerosity of Cartesian product. Proposition 4.22(d) of [Mendelson] p. 254. (Contributed by NM, 5-Jan-2004.) (Revised by Mario Carneiro, 15-Nov-2014.)

**Hypotheses**
Ref	Expression
xpcomen.1	⊢ 𝐴 ∈ V
xpcomen.2	⊢ 𝐵 ∈ V

**Assertion**
Ref	Expression
xpcomen	⊢ (𝐴 × 𝐵) ≈ (𝐵 × 𝐴)

Proof of Theorem xpcomen Dummy variable 𝑥 is distinct from all other variables.

Step	Hyp	Ref	Expression
1		xpcomen.1	. . 3 ⊢ 𝐴 ∈ V
2		xpcomen.2	. . 3 ⊢ 𝐵 ∈ V
3	1, 2	xpex 7698	. 2 ⊢ (𝐴 × 𝐵) ∈ V
4	2, 1	xpex 7698	. 2 ⊢ (𝐵 × 𝐴) ∈ V
5		eqid 2736	. . 3 ⊢ (𝑥 ∈ (𝐴 × 𝐵) ↦ ∪ ^◡{𝑥}) = (𝑥 ∈ (𝐴 × 𝐵) ↦ ∪ ^◡{𝑥})
6	5	xpcomf1o 8994	. 2 ⊢ (𝑥 ∈ (𝐴 × 𝐵) ↦ ∪ ^◡{𝑥}):(𝐴 × 𝐵)–1-1-onto→(𝐵 × 𝐴)
7		f1oen2g 8905	. 2 ⊢ (((𝐴 × 𝐵) ∈ V ∧ (𝐵 × 𝐴) ∈ V ∧ (𝑥 ∈ (𝐴 × 𝐵) ↦ ∪ ^◡{𝑥}):(𝐴 × 𝐵)–1-1-onto→(𝐵 × 𝐴)) → (𝐴 × 𝐵) ≈ (𝐵 × 𝐴))
8	3, 4, 6, 7	mp3an 1463	1 ⊢ (𝐴 × 𝐵) ≈ (𝐵 × 𝐴)

Colors of variables: wff setvar class

Syntax hints: ∈ wcel 2113 Vcvv 3440 {csn 4580 ∪ cuni 4863 class class class wbr 5098 ↦ cmpt 5179 × cxp 5622 ^◡ccnv 5623 –1-1-onto→wf1o 6491 ≈ cen 8880

This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1796 ax-4 1810 ax-5 1911 ax-6 1968 ax-7 2009 ax-8 2115 ax-9 2123 ax-10 2146 ax-11 2162 ax-12 2184 ax-ext 2708 ax-sep 5241 ax-nul 5251 ax-pow 5310 ax-pr 5377 ax-un 7680

This theorem depends on definitions: df-bi 207 df-an 396 df-or 848 df-3an 1088 df-tru 1544 df-fal 1554 df-ex 1781 df-nf 1785 df-sb 2068 df-mo 2539 df-eu 2569 df-clab 2715 df-cleq 2728 df-clel 2811 df-nfc 2885 df-ne 2933 df-ral 3052 df-rex 3061 df-rab 3400 df-v 3442 df-dif 3904 df-un 3906 df-in 3908 df-ss 3918 df-nul 4286 df-if 4480 df-pw 4556 df-sn 4581 df-pr 4583 df-op 4587 df-uni 4864 df-br 5099 df-opab 5161 df-mpt 5180 df-id 5519 df-xp 5630 df-rel 5631 df-cnv 5632 df-co 5633 df-dm 5634 df-rn 5635 df-iota 6448 df-fun 6494 df-fn 6495 df-f 6496 df-f1 6497 df-fo 6498 df-f1o 6499 df-fv 6500 df-1st 7933 df-2nd 7934 df-en 8884

This theorem is referenced by: xpcomeng 8997 ackbij1lem5 10133 hashxplem 14356

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