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Theorem eltail 35197
Description: An element of a tail. (Contributed by Jeff Hankins, 25-Nov-2009.) (Revised by Mario Carneiro, 24-Nov-2013.)
Hypothesis
Ref Expression
tailfval.1 𝑋 = dom 𝐷
Assertion
Ref Expression
eltail ((𝐷 ∈ DirRel ∧ 𝐴𝑋𝐵𝐶) → (𝐵 ∈ ((tail‘𝐷)‘𝐴) ↔ 𝐴𝐷𝐵))

Proof of Theorem eltail
StepHypRef Expression
1 tailfval.1 . . . . 5 𝑋 = dom 𝐷
21tailval 35196 . . . 4 ((𝐷 ∈ DirRel ∧ 𝐴𝑋) → ((tail‘𝐷)‘𝐴) = (𝐷 “ {𝐴}))
32eleq2d 2820 . . 3 ((𝐷 ∈ DirRel ∧ 𝐴𝑋) → (𝐵 ∈ ((tail‘𝐷)‘𝐴) ↔ 𝐵 ∈ (𝐷 “ {𝐴})))
433adant3 1133 . 2 ((𝐷 ∈ DirRel ∧ 𝐴𝑋𝐵𝐶) → (𝐵 ∈ ((tail‘𝐷)‘𝐴) ↔ 𝐵 ∈ (𝐷 “ {𝐴})))
5 elimasng 6084 . . . 4 ((𝐴𝑋𝐵𝐶) → (𝐵 ∈ (𝐷 “ {𝐴}) ↔ ⟨𝐴, 𝐵⟩ ∈ 𝐷))
6 df-br 5148 . . . 4 (𝐴𝐷𝐵 ↔ ⟨𝐴, 𝐵⟩ ∈ 𝐷)
75, 6bitr4di 289 . . 3 ((𝐴𝑋𝐵𝐶) → (𝐵 ∈ (𝐷 “ {𝐴}) ↔ 𝐴𝐷𝐵))
873adant1 1131 . 2 ((𝐷 ∈ DirRel ∧ 𝐴𝑋𝐵𝐶) → (𝐵 ∈ (𝐷 “ {𝐴}) ↔ 𝐴𝐷𝐵))
94, 8bitrd 279 1 ((𝐷 ∈ DirRel ∧ 𝐴𝑋𝐵𝐶) → (𝐵 ∈ ((tail‘𝐷)‘𝐴) ↔ 𝐴𝐷𝐵))
Colors of variables: wff setvar class
Syntax hints:  wi 4  wb 205  wa 397  w3a 1088   = wceq 1542  wcel 2107  {csn 4627  cop 4633   class class class wbr 5147  dom cdm 5675  cima 5678  cfv 6540  DirRelcdir 18543  tailctail 18544
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1798  ax-4 1812  ax-5 1914  ax-6 1972  ax-7 2012  ax-8 2109  ax-9 2117  ax-10 2138  ax-11 2155  ax-12 2172  ax-ext 2704  ax-rep 5284  ax-sep 5298  ax-nul 5305  ax-pr 5426  ax-un 7720
This theorem depends on definitions:  df-bi 206  df-an 398  df-or 847  df-3an 1090  df-tru 1545  df-fal 1555  df-ex 1783  df-nf 1787  df-sb 2069  df-mo 2535  df-eu 2564  df-clab 2711  df-cleq 2725  df-clel 2811  df-nfc 2886  df-ne 2942  df-ral 3063  df-rex 3072  df-reu 3378  df-rab 3434  df-v 3477  df-sbc 3777  df-csb 3893  df-dif 3950  df-un 3952  df-in 3954  df-ss 3964  df-nul 4322  df-if 4528  df-sn 4628  df-pr 4630  df-op 4634  df-uni 4908  df-iun 4998  df-br 5148  df-opab 5210  df-mpt 5231  df-id 5573  df-xp 5681  df-rel 5682  df-cnv 5683  df-co 5684  df-dm 5685  df-rn 5686  df-res 5687  df-ima 5688  df-iota 6492  df-fun 6542  df-fn 6543  df-f 6544  df-f1 6545  df-fo 6546  df-f1o 6547  df-fv 6548  df-dir 18545  df-tail 18546
This theorem is referenced by:  tailini  35199  tailfb  35200  filnetlem4  35204
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