Theorem xp1st 6125

Description: Location of the first element of a Cartesian product. (Contributed by Jeff Madsen, 2-Sep-2009.)

Assertion

Ref	Expression
xp1st	⊢ (𝐴 ∈ (𝐵 × 𝐶) → (1st ‘𝐴) ∈ 𝐵)

Proof of Theorem xp1st

Dummy variables 𝑏 𝑐 are mutually distinct and distinct from all other variables.

Step	Hyp	Ref	Expression
1		elxp 4615	. 2 ⊢ (𝐴 ∈ (𝐵 × 𝐶) ↔ ∃𝑏∃𝑐(𝐴 = ⟨𝑏, 𝑐⟩ ∧ (𝑏 ∈ 𝐵 ∧ 𝑐 ∈ 𝐶)))
2		vex 2724	. . . . . . 7 ⊢ 𝑏 ∈ V
3		vex 2724	. . . . . . 7 ⊢ 𝑐 ∈ V
4	2, 3	op1std 6108	. . . . . 6 ⊢ (𝐴 = ⟨𝑏, 𝑐⟩ → (1st ‘𝐴) = 𝑏)
5	4	eleq1d 2233	. . . . 5 ⊢ (𝐴 = ⟨𝑏, 𝑐⟩ → ((1st ‘𝐴) ∈ 𝐵 ↔ 𝑏 ∈ 𝐵))
6	5	biimpar 295	. . . 4 ⊢ ((𝐴 = ⟨𝑏, 𝑐⟩ ∧ 𝑏 ∈ 𝐵) → (1st ‘𝐴) ∈ 𝐵)
7	6	adantrr 471	. . 3 ⊢ ((𝐴 = ⟨𝑏, 𝑐⟩ ∧ (𝑏 ∈ 𝐵 ∧ 𝑐 ∈ 𝐶)) → (1st ‘𝐴) ∈ 𝐵)
8	7	exlimivv 1883	. 2 ⊢ (∃𝑏∃𝑐(𝐴 = ⟨𝑏, 𝑐⟩ ∧ (𝑏 ∈ 𝐵 ∧ 𝑐 ∈ 𝐶)) → (1st ‘𝐴) ∈ 𝐵)
9	1, 8	sylbi 120	1 ⊢ (𝐴 ∈ (𝐵 × 𝐶) → (1st ‘𝐴) ∈ 𝐵)

Syntax hints:   → wi 4   ∧ wa 103   = wceq 1342  ∃wex 1479   ∈ wcel 2135  ⟨cop 3573   × cxp 4596  ‘cfv 5182  1^st c1st 6098

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-io 699  ax-5 1434  ax-7 1435  ax-gen 1436  ax-ie1 1480  ax-ie2 1481  ax-8 1491  ax-10 1492  ax-11 1493  ax-i12 1494  ax-bndl 1496  ax-4 1497  ax-17 1513  ax-i9 1517  ax-ial 1521  ax-i5r 1522  ax-13 2137  ax-14 2138  ax-ext 2146  ax-sep 4094  ax-pow 4147  ax-pr 4181  ax-un 4405

This theorem depends on definitions:  df-bi 116  df-3an 969  df-tru 1345  df-nf 1448  df-sb 1750  df-eu 2016  df-mo 2017  df-clab 2151  df-cleq 2157  df-clel 2160  df-nfc 2295  df-ral 2447  df-rex 2448  df-v 2723  df-sbc 2947  df-un 3115  df-in 3117  df-ss 3124  df-pw 3555  df-sn 3576  df-pr 3577  df-op 3579  df-uni 3784  df-br 3977  df-opab 4038  df-mpt 4039  df-id 4265  df-xp 4604  df-rel 4605  df-cnv 4606  df-co 4607  df-dm 4608  df-rn 4609  df-iota 5147  df-fun 5184  df-fv 5190  df-1st 6100

This theorem is referenced by:  disjxp1  6195  xpf1o  6801  xpmapenlem  6806  djuf1olem  7009  eldju1st  7027  dfplpq2  7286  dfmpq2  7287  enqbreq2  7289  enqdc1  7294  mulpipq2  7303  preqlu  7404  elnp1st2nd  7408  cauappcvgprlemladd  7590  elreal2  7762  cnref1o  9579  frecuzrdgrrn  10333  frec2uzrdg  10334  frecuzrdgrcl  10335  frecuzrdgsuc  10339  frecuzrdgrclt  10340  frecuzrdgg  10341  frecuzrdgsuctlem  10348  seq3val  10383  seqvalcd  10384  fsum2dlemstep  11361  fisumcom2  11365  fprod2dlemstep  11549  fprodcom2fi  11553  eucalgval  11965  eucalginv  11967  eucalglt  11968  eucalg  11970  sqpweven  12084  2sqpwodd  12085  ctiunctlemudc  12307  tx2cn  12811  txdis  12818  txhmeo  12860  xmetxp  13048  xmetxpbl  13049  xmettxlem  13050  xmettx  13051