Theorem xp1st 6323

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 4740	. 2 ⊢ (𝐴 ∈ (𝐵 × 𝐶) ↔ ∃𝑏∃𝑐(𝐴 = ⟨𝑏, 𝑐⟩ ∧ (𝑏 ∈ 𝐵 ∧ 𝑐 ∈ 𝐶)))
2		vex 2803	. . . . . . 7 ⊢ 𝑏 ∈ V
3		vex 2803	. . . . . . 7 ⊢ 𝑐 ∈ V
4	2, 3	op1std 6306	. . . . . 6 ⊢ (𝐴 = ⟨𝑏, 𝑐⟩ → (1st ‘𝐴) = 𝑏)
5	4	eleq1d 2298	. . . . 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 479	. . 3 ⊢ ((𝐴 = ⟨𝑏, 𝑐⟩ ∧ (𝑏 ∈ 𝐵 ∧ 𝑐 ∈ 𝐶)) → (1st ‘𝐴) ∈ 𝐵)
8	7	exlimivv 1943	. 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 1395  ∃wex 1538   ∈ wcel 2200  ⟨cop 3670   × cxp 4721  ‘cfv 5324  1^st c1st 6296

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 714  ax-5 1493  ax-7 1494  ax-gen 1495  ax-ie1 1539  ax-ie2 1540  ax-8 1550  ax-10 1551  ax-11 1552  ax-i12 1553  ax-bndl 1555  ax-4 1556  ax-17 1572  ax-i9 1576  ax-ial 1580  ax-i5r 1581  ax-13 2202  ax-14 2203  ax-ext 2211  ax-sep 4205  ax-pow 4262  ax-pr 4297  ax-un 4528

This theorem depends on definitions:  df-bi 117  df-3an 1004  df-tru 1398  df-nf 1507  df-sb 1809  df-eu 2080  df-mo 2081  df-clab 2216  df-cleq 2222  df-clel 2225  df-nfc 2361  df-ral 2513  df-rex 2514  df-v 2802  df-sbc 3030  df-un 3202  df-in 3204  df-ss 3211  df-pw 3652  df-sn 3673  df-pr 3674  df-op 3676  df-uni 3892  df-br 4087  df-opab 4149  df-mpt 4150  df-id 4388  df-xp 4729  df-rel 4730  df-cnv 4731  df-co 4732  df-dm 4733  df-rn 4734  df-iota 5284  df-fun 5326  df-fv 5332  df-1st 6298

This theorem is referenced by:  disjxp1  6396  xpf1o  7025  xpmapenlem  7030  opabfi  7126  djuf1olem  7246  eldju1st  7264  exmidapne  7472  dfplpq2  7567  dfmpq2  7568  enqbreq2  7570  enqdc1  7575  mulpipq2  7584  preqlu  7685  elnp1st2nd  7689  cauappcvgprlemladd  7871  elreal2  8043  cnref1o  9878  frecuzrdgrrn  10663  frec2uzrdg  10664  frecuzrdgrcl  10665  frecuzrdgsuc  10669  frecuzrdgrclt  10670  frecuzrdgg  10671  frecuzrdgsuctlem  10678  seq3val  10715  seqvalcd  10716  fsum2dlemstep  11988  fisumcom2  11992  fprod2dlemstep  12176  fprodcom2fi  12180  eucalgval  12619  eucalginv  12621  eucalglt  12622  eucalg  12624  sqpweven  12740  2sqpwodd  12741  ctiunctlemudc  13051  xpsff1o  13425  tx2cn  14987  txdis  14994  txhmeo  15036  xmetxp  15224  xmetxpbl  15225  xmettxlem  15226  xmettx  15227  lgsquadlemofi  15798  lgsquadlem1  15799  lgsquadlem2  15800