Theorem bj-1nel0 34390

Description: 1_o does not belong to {∅}. (Contributed by BJ, 6-Apr-2019.)

Assertion

Ref	Expression
bj-1nel0	⊢ 1o ∉ {∅}

Proof of Theorem bj-1nel0

Step	Hyp	Ref	Expression
1		1n0 8102	. . . 4 ⊢ 1o ≠ ∅
2	1	neii 2989	. . 3 ⊢ ¬ 1o = ∅
3		elsni 4542	. . 3 ⊢ (1o ∈ {∅} → 1o = ∅)
4	2, 3	mto 200	. 2 ⊢ ¬ 1o ∈ {∅}
5	4	nelir 3094	1 ⊢ 1o ∉ {∅}

Syntax hints:   = wceq 1538   ∈ wcel 2111   ∉ wnel 3091  ∅c0 4243  {csn 4525  1_oc1o 8078

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1797  ax-4 1811  ax-5 1911  ax-6 1970  ax-7 2015  ax-8 2113  ax-9 2121  ax-ext 2770  ax-nul 5174

This theorem depends on definitions:  df-bi 210  df-an 400  df-or 845  df-ex 1782  df-sb 2070  df-clab 2777  df-cleq 2791  df-clel 2870  df-ne 2988  df-nel 3092  df-v 3443  df-dif 3884  df-un 3886  df-nul 4244  df-sn 4526  df-suc 6165  df-1o 8085

This theorem is referenced by: (None)