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 2145  Vcvv 3450  {csn 4584

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 2732

This proof depends on definitions:  df-bi 210  df-an 402  df-tru 1573  df-ex 1813  df-sb 2100  df-clab 2739  df-cleq 2752  df-clel 2835  df-sn 4585

This theorem is used by:  snsssn  4801  mosneq  4802  opth1  5451  propeqop  5484  opthwiener  5491  funsndifnop  7148  canth2  9128  axcc2lem  10438  hashge3el3dif  14552  dis2ndc  23686  axlowdim1  29416  selvply1rhmlema  34028  selvply1rhmlem1  34030  esplyfval1  34083  mh-inf3sn  37161  bj-snsetex  37707  poimirlem13  38382  poimirlem14  38383  wopprc  43871  snen1g  44364  mnuprdlem2  45097  hoidmv1le  47422  fsetsnf1  47940