Theorem n0ii 4288

Description: If a class has elements, then it is not empty. Inference associated with n0i 4285. (Contributed by BJ, 15-Jul-2021.)

Hypothesis

Ref	Expression
n0ii.1	⊢ 𝐴 ∈ 𝐵

Assertion

Ref	Expression
n0ii	⊢ ¬ 𝐵 = ∅

Proof of Theorem n0ii

Step	Hyp	Ref	Expression
1		n0ii.1	. 2 ⊢ 𝐴 ∈ 𝐵
2		n0i 4285	. 2 ⊢ (𝐴 ∈ 𝐵 → ¬ 𝐵 = ∅)
3	1, 2	ax-mp 5	1 ⊢ ¬ 𝐵 = ∅

This proof depends on syntax axioms:  ¬ wn 3   = wceq 1569   ∈ wcel 2144  ∅c0 4277

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-tru 1572  df-fal 1582  df-ex 1812  df-sb 2099  df-clab 2739  df-cleq 2752  df-clel 2835  df-dif 4046  df-nul 4278

This theorem is used by:  iin0  5323  snsn0non  6491  tfrlem16  8406  hon0  32402  dmadjrnb  32515  bnj98  35545  noinfepfnregs  35858  prv0  36283  dvnprodlem3  47065