Description: Define the set of positive surreal integers. (Contributed by Scott Fenton, 17-Mar-2025)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | df-nns | ⊢ ℕs = ( ℕ0s ∖ { 0s } ) | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 0 | cnns | ⊢ ℕs | |
| 1 | cnn0s | ⊢ ℕ0s | |
| 2 | c0s | ⊢ 0s | |
| 3 | 2 | csn | ⊢ { 0s } | 
| 4 | 1 3 | cdif | ⊢ ( ℕ0s ∖ { 0s } ) | 
| 5 | 0 4 | wceq | ⊢ ℕs = ( ℕ0s ∖ { 0s } ) |