Theorem sneqr 4800

Description: If the singletons of two sets are equal, the two sets are equal. Part of Exercise 4 of [TakeutiZaring] p. 15. (Contributed by NM, 27-Aug-1993.)

Hypothesis

Ref	Expression
sneqr.1	⊢ 𝐴 ∈ V

Assertion

Ref	Expression
sneqr	⊢ ({𝐴} = {𝐵} → 𝐴 = 𝐵)

Proof of Theorem sneqr

Step	Hyp	Ref	Expression
1		sneqr.1	. 2 ⊢ 𝐴 ∈ V
2		sneqrg 4799	. 2 ⊢ (𝐴 ∈ V → ({𝐴} = {𝐵} → 𝐴 = 𝐵))
3	1, 2	ax-mp 5	1 ⊢ ({𝐴} = {𝐵} → 𝐴 = 𝐵)

This proof depends on syntax axioms:   → wi 4   = wceq 1570   ∈ wcel 2147  Vcvv 3454  {csn 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 1945  ax-6 2002  ax-7 2043  ax-8 2149  ax-9 2157  ax-ext 2735

This proof depends on definitions:  df-bi 210  df-an 402  df-tru 1573  df-ex 1813  df-sb 2102  df-clab 2742  df-cleq 2755  df-clel 2839  df-sn 4589

This theorem is used by:  snsssn  4801  mosneq  4802  opth1  5451  propeqop  5486  opthwiener  5494  funsndifnop  7187  canth2  9187  axcc2lem  10553  hashge3el3dif  14673  dis2ndc  23834  axlowdim1  29594  selvply1rhmlema  34261  selvply1rhmlem1  34263  esplyfval1  34316  mh-inf3sn  37545  bj-snsetex  38091  poimirlem13  38819  poimirlem14  38820  wopprc  44303  snen1g  44786  mnuprdlem2  45518  hoidmv1le  47877  fsetsnf1  48395