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Theorem xpinpreima 30253
 Description: Rewrite the cartesian product of two sets as the intersection of their preimage by 1st and 2nd, the projections on the first and second elements. (Contributed by Thierry Arnoux, 22-Sep-2017.)
Assertion
Ref Expression
xpinpreima (𝐴 × 𝐵) = (((1st ↾ (V × V)) “ 𝐴) ∩ ((2nd ↾ (V × V)) “ 𝐵))

Proof of Theorem xpinpreima
Dummy variable 𝑟 is distinct from all other variables.
StepHypRef Expression
1 inrab 4034 . 2 ({𝑟 ∈ (V × V) ∣ (1st𝑟) ∈ 𝐴} ∩ {𝑟 ∈ (V × V) ∣ (2nd𝑟) ∈ 𝐵}) = {𝑟 ∈ (V × V) ∣ ((1st𝑟) ∈ 𝐴 ∧ (2nd𝑟) ∈ 𝐵)}
2 f1stres 7349 . . . . 5 (1st ↾ (V × V)):(V × V)⟶V
3 ffn 6198 . . . . 5 ((1st ↾ (V × V)):(V × V)⟶V → (1st ↾ (V × V)) Fn (V × V))
4 fncnvima2 6494 . . . . 5 ((1st ↾ (V × V)) Fn (V × V) → ((1st ↾ (V × V)) “ 𝐴) = {𝑟 ∈ (V × V) ∣ ((1st ↾ (V × V))‘𝑟) ∈ 𝐴})
52, 3, 4mp2b 10 . . . 4 ((1st ↾ (V × V)) “ 𝐴) = {𝑟 ∈ (V × V) ∣ ((1st ↾ (V × V))‘𝑟) ∈ 𝐴}
6 fvres 6360 . . . . . 6 (𝑟 ∈ (V × V) → ((1st ↾ (V × V))‘𝑟) = (1st𝑟))
76eleq1d 2816 . . . . 5 (𝑟 ∈ (V × V) → (((1st ↾ (V × V))‘𝑟) ∈ 𝐴 ↔ (1st𝑟) ∈ 𝐴))
87rabbiia 3316 . . . 4 {𝑟 ∈ (V × V) ∣ ((1st ↾ (V × V))‘𝑟) ∈ 𝐴} = {𝑟 ∈ (V × V) ∣ (1st𝑟) ∈ 𝐴}
95, 8eqtri 2774 . . 3 ((1st ↾ (V × V)) “ 𝐴) = {𝑟 ∈ (V × V) ∣ (1st𝑟) ∈ 𝐴}
10 f2ndres 7350 . . . . 5 (2nd ↾ (V × V)):(V × V)⟶V
11 ffn 6198 . . . . 5 ((2nd ↾ (V × V)):(V × V)⟶V → (2nd ↾ (V × V)) Fn (V × V))
12 fncnvima2 6494 . . . . 5 ((2nd ↾ (V × V)) Fn (V × V) → ((2nd ↾ (V × V)) “ 𝐵) = {𝑟 ∈ (V × V) ∣ ((2nd ↾ (V × V))‘𝑟) ∈ 𝐵})
1310, 11, 12mp2b 10 . . . 4 ((2nd ↾ (V × V)) “ 𝐵) = {𝑟 ∈ (V × V) ∣ ((2nd ↾ (V × V))‘𝑟) ∈ 𝐵}
14 fvres 6360 . . . . . 6 (𝑟 ∈ (V × V) → ((2nd ↾ (V × V))‘𝑟) = (2nd𝑟))
1514eleq1d 2816 . . . . 5 (𝑟 ∈ (V × V) → (((2nd ↾ (V × V))‘𝑟) ∈ 𝐵 ↔ (2nd𝑟) ∈ 𝐵))
1615rabbiia 3316 . . . 4 {𝑟 ∈ (V × V) ∣ ((2nd ↾ (V × V))‘𝑟) ∈ 𝐵} = {𝑟 ∈ (V × V) ∣ (2nd𝑟) ∈ 𝐵}
1713, 16eqtri 2774 . . 3 ((2nd ↾ (V × V)) “ 𝐵) = {𝑟 ∈ (V × V) ∣ (2nd𝑟) ∈ 𝐵}
189, 17ineq12i 3947 . 2 (((1st ↾ (V × V)) “ 𝐴) ∩ ((2nd ↾ (V × V)) “ 𝐵)) = ({𝑟 ∈ (V × V) ∣ (1st𝑟) ∈ 𝐴} ∩ {𝑟 ∈ (V × V) ∣ (2nd𝑟) ∈ 𝐵})
19 xp2 7362 . 2 (𝐴 × 𝐵) = {𝑟 ∈ (V × V) ∣ ((1st𝑟) ∈ 𝐴 ∧ (2nd𝑟) ∈ 𝐵)}
201, 18, 193eqtr4ri 2785 1 (𝐴 × 𝐵) = (((1st ↾ (V × V)) “ 𝐴) ∩ ((2nd ↾ (V × V)) “ 𝐵))
 Colors of variables: wff setvar class Syntax hints:   ∧ wa 383   = wceq 1624   ∈ wcel 2131  {crab 3046  Vcvv 3332   ∩ cin 3706   × cxp 5256  ◡ccnv 5257   ↾ cres 5260   “ cima 5261   Fn wfn 6036  ⟶wf 6037  ‘cfv 6041  1st c1st 7323  2nd c2nd 7324 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1863  ax-4 1878  ax-5 1980  ax-6 2046  ax-7 2082  ax-8 2133  ax-9 2140  ax-10 2160  ax-11 2175  ax-12 2188  ax-13 2383  ax-ext 2732  ax-sep 4925  ax-nul 4933  ax-pow 4984  ax-pr 5047  ax-un 7106 This theorem depends on definitions:  df-bi 197  df-or 384  df-an 385  df-3an 1074  df-tru 1627  df-ex 1846  df-nf 1851  df-sb 2039  df-eu 2603  df-mo 2604  df-clab 2739  df-cleq 2745  df-clel 2748  df-nfc 2883  df-ne 2925  df-ral 3047  df-rex 3048  df-rab 3051  df-v 3334  df-sbc 3569  df-csb 3667  df-dif 3710  df-un 3712  df-in 3714  df-ss 3721  df-nul 4051  df-if 4223  df-sn 4314  df-pr 4316  df-op 4320  df-uni 4581  df-iun 4666  df-br 4797  df-opab 4857  df-mpt 4874  df-id 5166  df-xp 5264  df-rel 5265  df-cnv 5266  df-co 5267  df-dm 5268  df-rn 5269  df-res 5270  df-ima 5271  df-iota 6004  df-fun 6043  df-fn 6044  df-f 6045  df-fv 6049  df-1st 7325  df-2nd 7326 This theorem is referenced by: (None)
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