Description: A finite set is countable (weaker version of isfinite ). (Contributed by Thierry Arnoux, 27-Mar-2018)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | fict | ⊢ ( 𝐴 ∈ Fin → 𝐴 ≼ ω ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | isfinite | ⊢ ( 𝐴 ∈ Fin ↔ 𝐴 ≺ ω ) | |
| 2 | sdomdom | ⊢ ( 𝐴 ≺ ω → 𝐴 ≼ ω ) | |
| 3 | 1 2 | sylbi | ⊢ ( 𝐴 ∈ Fin → 𝐴 ≼ ω ) |