Theorem eltp 4633

Description: A member of an unordered triple of classes is one of them. Special case of Exercise 1 of [TakeutiZaring] p. 17. (Contributed by NM, 8-Apr-1994.) (Revised by Mario Carneiro, 11-Feb-2015.)

Hypothesis

Ref	Expression
eltp.1	⊢ 𝐴 ∈ V

Assertion

Ref	Expression
eltp	⊢ (𝐴 ∈ {𝐵, 𝐶, 𝐷} ↔ (𝐴 = 𝐵 ∨ 𝐴 = 𝐶 ∨ 𝐴 = 𝐷))

Proof of Theorem eltp

Step	Hyp	Ref	Expression
1		eltp.1	. 2 ⊢ 𝐴 ∈ V
2		eltpg 4630	. 2 ⊢ (𝐴 ∈ V → (𝐴 ∈ {𝐵, 𝐶, 𝐷} ↔ (𝐴 = 𝐵 ∨ 𝐴 = 𝐶 ∨ 𝐴 = 𝐷)))
3	1, 2	ax-mp 5	1 ⊢ (𝐴 ∈ {𝐵, 𝐶, 𝐷} ↔ (𝐴 = 𝐵 ∨ 𝐴 = 𝐶 ∨ 𝐴 = 𝐷))

Syntax hints:   ↔ wb 206   ∨ w3o 1086   = wceq 1542   ∈ wcel 2114  Vcvv 3429  {ctp 4571

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1797  ax-4 1811  ax-5 1912  ax-6 1969  ax-7 2010  ax-8 2116  ax-9 2124  ax-ext 2708

This theorem depends on definitions:  df-bi 207  df-an 396  df-or 849  df-3or 1088  df-tru 1545  df-ex 1782  df-sb 2069  df-clab 2715  df-cleq 2728  df-clel 2811  df-v 3431  df-un 3894  df-sn 4568  df-pr 4570  df-tp 4572

This theorem is referenced by:  dftp2  4635  tpid1  4712  tpid2  4714  brtp  5478  tpres  7156  fntpb  7164  bpoly3  16023  cnfldfun  21366  gausslemma2dlem0i  27327  2lgsoddprm  27379  ltssolem1  27639  nb3grprlem1  29449  frgr3vlem1  30343  frgr3vlem2  30344  prodtp  32900  s3f1  33007  hgt750lemb  34800  fmtno4prmfac  48035  usgrexmpl2nb0  48507  usgrexmpl2nb3  48510  usgrexmpl2trifr  48513  gpgnbgrvtx0  48550  gpgnbgrvtx1  48551