Theorem eltp 4646

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 4643	. 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 1569   ∈ wcel 2144  Vcvv 3450  {ctp 4588

This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1827  ax-4 1841  ax-5 1942  ax-6 1999  ax-7 2040  ax-8 2146  ax-9 2154  ax-ext 2732

This proof depends on definitions:  df-bi 210  df-an 402  df-or 862  df-3or 1104  df-tru 1572  df-ex 1812  df-sb 2099  df-clab 2739  df-cleq 2752  df-clel 2835  df-v 3452  df-un 4151  df-sn 4585  df-pr 4587  df-tp 4589

This theorem is used by:  dftp2  4648  tpid1  4725  tpid2  4727  brtp  5496  fvtp0  7206  tpres  7207  fntpb  7215  bpoly3  16229  cnfldfun  21697  gausslemma2dlem0i  27696  2lgsoddprm  27748  ltssolem1  28037  nb3grprlem1  29966  frgr3vlem1  30879  frgr3vlem2  30880  prodtp  33464  s3f1  33557  hgt750lemb  35331  fmtno4prmfac  48750  usgrexmpl2nb0  49222  usgrexmpl2nb3  49225  usgrexmpl2trifr  49228  gpgnbgrvtx0  49265  gpgnbgrvtx1  49266