Theorem eltp 4650

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 4647	. 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))

This proof depends on syntax axioms:   ↔ wb 209   ∨ w3o 1102   = wceq 1570   ∈ wcel 2145  Vcvv 3451  {ctp 4588

This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1828  ax-4 1842  ax-5 1943  ax-6 2000  ax-7 2041  ax-8 2147  ax-9 2155  ax-ext 2733

This proof depends on definitions:  df-bi 210  df-an 402  df-or 862  df-3or 1104  df-tru 1573  df-ex 1813  df-sb 2100  df-clab 2740  df-cleq 2753  df-clel 2836  df-v 3453  df-un 3904  df-sn 4585  df-pr 4587  df-tp 4589

This theorem is used by:  dftp2  4652  tpid1  4729  tpid2  4731  brtp  5497  fvtp0  7198  tpres  7199  fntpb  7207  bpoly3  16204  cnfldfun  21672  gausslemma2dlem0i  27673  2lgsoddprm  27725  ltssolem1  28014  nb3grprlem1  29943  frgr3vlem1  30856  frgr3vlem2  30857  prodtp  33400  s3f1  33493  hgt750lemb  35268  fmtno4prmfac  48601  usgrexmpl2nb0  49073  usgrexmpl2nb3  49076  usgrexmpl2trifr  49079  gpgnbgrvtx0  49116  gpgnbgrvtx1  49117