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Theorem xp1st 5895
Description: Location of the first element of a Cartesian product. (Contributed by Jeff Madsen, 2-Sep-2009.)
Assertion
Ref Expression
xp1st (𝐴 ∈ (𝐵 × 𝐶) → (1st𝐴) ∈ 𝐵)

Proof of Theorem xp1st
Dummy variables 𝑏 𝑐 are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 elxp 4430 . 2 (𝐴 ∈ (𝐵 × 𝐶) ↔ ∃𝑏𝑐(𝐴 = ⟨𝑏, 𝑐⟩ ∧ (𝑏𝐵𝑐𝐶)))
2 vex 2618 . . . . . . 7 𝑏 ∈ V
3 vex 2618 . . . . . . 7 𝑐 ∈ V
42, 3op1std 5878 . . . . . 6 (𝐴 = ⟨𝑏, 𝑐⟩ → (1st𝐴) = 𝑏)
54eleq1d 2153 . . . . 5 (𝐴 = ⟨𝑏, 𝑐⟩ → ((1st𝐴) ∈ 𝐵𝑏𝐵))
65biimpar 291 . . . 4 ((𝐴 = ⟨𝑏, 𝑐⟩ ∧ 𝑏𝐵) → (1st𝐴) ∈ 𝐵)
76adantrr 463 . . 3 ((𝐴 = ⟨𝑏, 𝑐⟩ ∧ (𝑏𝐵𝑐𝐶)) → (1st𝐴) ∈ 𝐵)
87exlimivv 1821 . 2 (∃𝑏𝑐(𝐴 = ⟨𝑏, 𝑐⟩ ∧ (𝑏𝐵𝑐𝐶)) → (1st𝐴) ∈ 𝐵)
91, 8sylbi 119 1 (𝐴 ∈ (𝐵 × 𝐶) → (1st𝐴) ∈ 𝐵)
Colors of variables: wff set class
Syntax hints:  wi 4  wa 102   = wceq 1287  wex 1424  wcel 1436  cop 3434   × cxp 4411  cfv 4983  1st c1st 5868
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 104  ax-ia2 105  ax-ia3 106  ax-io 663  ax-5 1379  ax-7 1380  ax-gen 1381  ax-ie1 1425  ax-ie2 1426  ax-8 1438  ax-10 1439  ax-11 1440  ax-i12 1441  ax-bndl 1442  ax-4 1443  ax-13 1447  ax-14 1448  ax-17 1462  ax-i9 1466  ax-ial 1470  ax-i5r 1471  ax-ext 2067  ax-sep 3934  ax-pow 3986  ax-pr 4012  ax-un 4236
This theorem depends on definitions:  df-bi 115  df-3an 924  df-tru 1290  df-nf 1393  df-sb 1690  df-eu 1948  df-mo 1949  df-clab 2072  df-cleq 2078  df-clel 2081  df-nfc 2214  df-ral 2360  df-rex 2361  df-v 2617  df-sbc 2830  df-un 2992  df-in 2994  df-ss 3001  df-pw 3417  df-sn 3437  df-pr 3438  df-op 3440  df-uni 3639  df-br 3823  df-opab 3877  df-mpt 3878  df-id 4096  df-xp 4419  df-rel 4420  df-cnv 4421  df-co 4422  df-dm 4423  df-rn 4424  df-iota 4948  df-fun 4985  df-fv 4991  df-1st 5870
This theorem is referenced by:  xpf1o  6514  xpmapenlem  6519  djuf1olem  6692  djur  6704  eldju1st  6709  dfplpq2  6860  dfmpq2  6861  enqbreq2  6863  enqdc1  6868  mulpipq2  6877  preqlu  6978  elnp1st2nd  6982  cauappcvgprlemladd  7164  elreal2  7315  cnref1o  9068  frecuzrdgrrn  9746  frec2uzrdg  9747  frecuzrdgrcl  9748  frecuzrdgsuc  9752  frecuzrdgrclt  9753  frecuzrdgg  9754  frecuzrdgsuctlem  9761  iseqvalt  9793  eucalgval  10942  eucalginv  10944  eucalglt  10945  eucialg  10947  sqpweven  11059  2sqpwodd  11060
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