Theorem xp1st 6361

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 4768	. 2 ⊢ (𝐴 ∈ (𝐵 × 𝐶) ↔ ∃𝑏∃𝑐(𝐴 = ⟨𝑏, 𝑐⟩ ∧ (𝑏 ∈ 𝐵 ∧ 𝑐 ∈ 𝐶)))
2		vex 2818	. . . . . . 7 ⊢ 𝑏 ∈ V
3		vex 2818	. . . . . . 7 ⊢ 𝑐 ∈ V
4	2, 3	op1std 6344	. . . . . 6 ⊢ (𝐴 = ⟨𝑏, 𝑐⟩ → (1st ‘𝐴) = 𝑏)
5	4	eleq1d 2303	. . . . 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 1948	. 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 1398  ∃wex 1541   ∈ wcel 2205  ⟨cop 3694   × cxp 4749  ‘cfv 5354  1^st c1st 6334

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 717  ax-5 1496  ax-7 1497  ax-gen 1498  ax-ie1 1542  ax-ie2 1543  ax-8 1553  ax-10 1554  ax-11 1555  ax-i12 1556  ax-bndl 1558  ax-4 1559  ax-17 1575  ax-i9 1579  ax-ial 1583  ax-i5r 1584  ax-13 2207  ax-14 2208  ax-ext 2216  ax-sep 4230  ax-pow 4289  ax-pr 4324  ax-un 4556

This theorem depends on definitions:  df-bi 117  df-3an 1007  df-tru 1401  df-nf 1510  df-sb 1812  df-eu 2085  df-mo 2086  df-clab 2221  df-cleq 2227  df-clel 2230  df-nfc 2375  df-ral 2527  df-rex 2528  df-v 2817  df-sbc 3045  df-un 3217  df-in 3219  df-ss 3226  df-pw 3673  df-sn 3697  df-pr 3698  df-op 3700  df-uni 3917  df-br 4112  df-opab 4174  df-mpt 4175  df-id 4416  df-xp 4757  df-rel 4758  df-cnv 4759  df-co 4760  df-dm 4761  df-rn 4762  df-iota 5314  df-fun 5356  df-fv 5362  df-1st 6336

This theorem is referenced by:  disjxp1  6434  xpf1o  7099  xpmapenlem  7104  mapunen  7106  opabfi  7202  djuf1olem  7346  eldju1st  7364  exmidapne  7579  dfplpq2  7674  dfmpq2  7675  enqbreq2  7677  enqdc1  7682  mulpipq2  7691  preqlu  7792  elnp1st2nd  7796  cauappcvgprlemladd  7978  elreal2  8150  cnref1o  9989  frecuzrdgrrn  10777  frec2uzrdg  10778  frecuzrdgrcl  10779  frecuzrdgsuc  10783  frecuzrdgrclt  10784  frecuzrdgg  10785  frecuzrdgsuctlem  10792  seq3val  10829  seqvalcd  10830  fsum2dlemstep  12128  fisumcom2  12132  fprod2dlemstep  12316  fprodcom2fi  12320  eucalgval  12759  eucalginv  12761  eucalglt  12762  eucalg  12764  sqpweven  12880  2sqpwodd  12881  ctiunctlemudc  13209  xpsff1o  13583  tx2cn  15184  txdis  15191  txhmeo  15233  xmetxp  15421  xmetxpbl  15422  xmettxlem  15423  xmettx  15424  lgsquadlemofi  15998  lgsquadlem1  15999  lgsquadlem2  16000