Theorem xp1st 6232

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 4681	. 2 ⊢ (𝐴 ∈ (𝐵 × 𝐶) ↔ ∃𝑏∃𝑐(𝐴 = ⟨𝑏, 𝑐⟩ ∧ (𝑏 ∈ 𝐵 ∧ 𝑐 ∈ 𝐶)))
2		vex 2766	. . . . . . 7 ⊢ 𝑏 ∈ V
3		vex 2766	. . . . . . 7 ⊢ 𝑐 ∈ V
4	2, 3	op1std 6215	. . . . . 6 ⊢ (𝐴 = ⟨𝑏, 𝑐⟩ → (1st ‘𝐴) = 𝑏)
5	4	eleq1d 2265	. . . . 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 1911	. 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 1364  ∃wex 1506   ∈ wcel 2167  ⟨cop 3626   × cxp 4662  ‘cfv 5259  1^st c1st 6205

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 710  ax-5 1461  ax-7 1462  ax-gen 1463  ax-ie1 1507  ax-ie2 1508  ax-8 1518  ax-10 1519  ax-11 1520  ax-i12 1521  ax-bndl 1523  ax-4 1524  ax-17 1540  ax-i9 1544  ax-ial 1548  ax-i5r 1549  ax-13 2169  ax-14 2170  ax-ext 2178  ax-sep 4152  ax-pow 4208  ax-pr 4243  ax-un 4469

This theorem depends on definitions:  df-bi 117  df-3an 982  df-tru 1367  df-nf 1475  df-sb 1777  df-eu 2048  df-mo 2049  df-clab 2183  df-cleq 2189  df-clel 2192  df-nfc 2328  df-ral 2480  df-rex 2481  df-v 2765  df-sbc 2990  df-un 3161  df-in 3163  df-ss 3170  df-pw 3608  df-sn 3629  df-pr 3630  df-op 3632  df-uni 3841  df-br 4035  df-opab 4096  df-mpt 4097  df-id 4329  df-xp 4670  df-rel 4671  df-cnv 4672  df-co 4673  df-dm 4674  df-rn 4675  df-iota 5220  df-fun 5261  df-fv 5267  df-1st 6207

This theorem is referenced by:  disjxp1  6303  xpf1o  6914  xpmapenlem  6919  opabfi  7008  djuf1olem  7128  eldju1st  7146  exmidapne  7343  dfplpq2  7438  dfmpq2  7439  enqbreq2  7441  enqdc1  7446  mulpipq2  7455  preqlu  7556  elnp1st2nd  7560  cauappcvgprlemladd  7742  elreal2  7914  cnref1o  9742  frecuzrdgrrn  10517  frec2uzrdg  10518  frecuzrdgrcl  10519  frecuzrdgsuc  10523  frecuzrdgrclt  10524  frecuzrdgg  10525  frecuzrdgsuctlem  10532  seq3val  10569  seqvalcd  10570  fsum2dlemstep  11616  fisumcom2  11620  fprod2dlemstep  11804  fprodcom2fi  11808  eucalgval  12247  eucalginv  12249  eucalglt  12250  eucalg  12252  sqpweven  12368  2sqpwodd  12369  ctiunctlemudc  12679  xpsff1o  13051  tx2cn  14590  txdis  14597  txhmeo  14639  xmetxp  14827  xmetxpbl  14828  xmettxlem  14829  xmettx  14830  lgsquadlemofi  15401  lgsquadlem1  15402  lgsquadlem2  15403