Theorem xp1st 6393

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 4789	. 2 ⊢ (𝐴 ∈ (𝐵 × 𝐶) ↔ ∃𝑏∃𝑐(𝐴 = ⟨𝑏, 𝑐⟩ ∧ (𝑏 ∈ 𝐵 ∧ 𝑐 ∈ 𝐶)))
2		vex 2824	. . . . . . 7 ⊢ 𝑏 ∈ V
3		vex 2824	. . . . . . 7 ⊢ 𝑐 ∈ V
4	2, 3	op1std 6376	. . . . . 6 ⊢ (𝐴 = ⟨𝑏, 𝑐⟩ → (1st ‘𝐴) = 𝑏)
5	4	eleq1d 2307	. . . . 5 ⊢ (𝐴 = ⟨𝑏, 𝑐⟩ → ((1st ‘𝐴) ∈ 𝐵 ↔ 𝑏 ∈ 𝐵))
6	5	biimpar 297	. . . 4 ⊢ ((𝐴 = ⟨𝑏, 𝑐⟩ ∧ 𝑏 ∈ 𝐵) → (1st ‘𝐴) ∈ 𝐵)
7	6	adantrr 483	. . 3 ⊢ ((𝐴 = ⟨𝑏, 𝑐⟩ ∧ (𝑏 ∈ 𝐵 ∧ 𝑐 ∈ 𝐶)) → (1st ‘𝐴) ∈ 𝐵)
8	7	exlimivv 1952	. 2 ⊢ (∃𝑏∃𝑐(𝐴 = ⟨𝑏, 𝑐⟩ ∧ (𝑏 ∈ 𝐵 ∧ 𝑐 ∈ 𝐶)) → (1st ‘𝐴) ∈ 𝐵)
9	1, 8	sylbi 121	1 ⊢ (𝐴 ∈ (𝐵 × 𝐶) → (1st ‘𝐴) ∈ 𝐵)

Syntax hints:   → wi 4   ∧ wa 104   = wceq 1402  ∃wex 1545   ∈ wcel 2209  ⟨cop 3711   × cxp 4770  ‘cfv 5375  1^st c1st 6366

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-io 721  ax-5 1500  ax-7 1501  ax-gen 1502  ax-ie1 1546  ax-ie2 1547  ax-8 1557  ax-10 1558  ax-11 1559  ax-i12 1560  ax-bndl 1562  ax-4 1563  ax-17 1579  ax-i9 1583  ax-ial 1587  ax-i5r 1588  ax-14 2212  ax-ext 2220  ax-sep 4247  ax-pow 4309  ax-pr 4344  ax-un 4576

This theorem depends on definitions:  df-bi 117  df-3an 1011  df-tru 1405  df-nf 1514  df-sb 1816  df-eu 2089  df-mo 2090  df-clab 2225  df-cleq 2231  df-clel 2234  df-nfc 2381  df-ral 2533  df-rex 2534  df-v 2823  df-sbc 3052  df-un 3224  df-in 3226  df-ss 3233  df-pw 3690  df-sn 3714  df-pr 3715  df-op 3717  df-uni 3934  df-br 4129  df-opab 4191  df-mpt 4192  df-id 4436  df-xp 4778  df-rel 4779  df-cnv 4780  df-co 4781  df-dm 4782  df-rn 4783  df-iota 5335  df-fun 5377  df-fv 5383  df-1st 6368

This theorem is referenced by:  disjxp1  6466  xpf1o  7138  xpmapenlem  7143  mapunen  7145  opabfi  7241  djuf1olem  7387  eldju1st  7405  exmidapne  7620  dfplpq2  7715  dfmpq2  7716  enqbreq2  7718  enqdc1  7723  mulpipq2  7732  preqlu  7833  elnp1st2nd  7837  cauappcvgprlemladd  8019  elreal2  8191  cnref1o  10034  frecuzrdgrrn  10828  frec2uzrdg  10829  frecuzrdgrcl  10830  frecuzrdgsuc  10834  frecuzrdgrclt  10835  frecuzrdgg  10836  frecuzrdgsuctlem  10843  seq3val  10880  seqvalcd  10881  fsum2dlemstep  12184  fisumcom2  12188  fprod2dlemstep  12372  fprodcom2fi  12376  eucalgval  12815  eucalginv  12817  eucalglt  12818  eucalg  12820  sqpweven  12936  2sqpwodd  12937  ctiunctlemudc  13311  xpsff1o  13653  tx2cn  15354  txdis  15361  txhmeo  15403  xmetxp  15591  xmetxpbl  15592  xmettxlem  15593  xmettx  15594  lgsquadlemofi  16178  lgsquadlem1  16179  lgsquadlem2  16180