Metamath Proof Explorer


Theorem ensucne0

Description: A class equinumerous to a successor is never empty. (Contributed by RP, 11-Nov-2023) (Proof shortened by SN, 16-Nov-2023)

Ref Expression
Assertion ensucne0 ( 𝐴 ≈ suc 𝐵𝐴 ≠ ∅ )

Proof

Step Hyp Ref Expression
1 nsuceq0 suc 𝐵 ≠ ∅
2 ensymb ( ∅ ≈ suc 𝐵 ↔ suc 𝐵 ≈ ∅ )
3 en0 ( suc 𝐵 ≈ ∅ ↔ suc 𝐵 = ∅ )
4 2 3 bitri ( ∅ ≈ suc 𝐵 ↔ suc 𝐵 = ∅ )
5 1 4 nemtbir ¬ ∅ ≈ suc 𝐵
6 breq1 ( 𝐴 = ∅ → ( 𝐴 ≈ suc 𝐵 ↔ ∅ ≈ suc 𝐵 ) )
7 5 6 mtbiri ( 𝐴 = ∅ → ¬ 𝐴 ≈ suc 𝐵 )
8 7 necon2ai ( 𝐴 ≈ suc 𝐵𝐴 ≠ ∅ )