Theorem ondif1i 42477

Description: Ordinal zero is less than every non-zero ordinal, class difference version. Theorem 1.10 of [Schloeder] p. 2. See ondif1 8507. (Contributed by RP, 16-Jan-2025.)

Assertion

Ref	Expression
ondif1i	⊢ (𝐴 ∈ (On ∖ 1o) → ∅ ∈ 𝐴)

Proof of Theorem ondif1i

Step	Hyp	Ref	Expression
1		ondif1 8507	. 2 ⊢ (𝐴 ∈ (On ∖ 1o) ↔ (𝐴 ∈ On ∧ ∅ ∈ 𝐴))
2	1	simprbi 496	1 ⊢ (𝐴 ∈ (On ∖ 1o) → ∅ ∈ 𝐴)

Syntax hints:   → wi 4   ∈ wcel 2105   ∖ cdif 3945  ∅c0 4322  Oncon0 6364  1_oc1o 8465

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1796  ax-4 1810  ax-5 1912  ax-6 1970  ax-7 2010  ax-8 2107  ax-9 2115  ax-ext 2702  ax-sep 5299  ax-nul 5306  ax-pr 5427

This theorem depends on definitions:  df-bi 206  df-an 396  df-or 845  df-3or 1087  df-3an 1088  df-tru 1543  df-fal 1553  df-ex 1781  df-sb 2067  df-clab 2709  df-cleq 2723  df-clel 2809  df-ne 2940  df-ral 3061  df-rex 3070  df-rab 3432  df-v 3475  df-dif 3951  df-un 3953  df-in 3955  df-ss 3965  df-pss 3967  df-nul 4323  df-if 4529  df-pw 4604  df-sn 4629  df-pr 4631  df-op 4635  df-uni 4909  df-br 5149  df-opab 5211  df-tr 5266  df-eprel 5580  df-po 5588  df-so 5589  df-fr 5631  df-we 5633  df-ord 6367  df-on 6368  df-suc 6370  df-1o 8472

This theorem is referenced by: (None)