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Description: A natural number is ordinal. (Contributed by NM, 17-Oct-1995)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | nnord | ⊢ ( 𝐴 ∈ ω → Ord 𝐴 ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | nnon | ⊢ ( 𝐴 ∈ ω → 𝐴 ∈ On ) | |
| 2 | eloni | ⊢ ( 𝐴 ∈ On → Ord 𝐴 ) | |
| 3 | 1 2 | syl | ⊢ ( 𝐴 ∈ ω → Ord 𝐴 ) |