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Mirrors > Home > ILE Home > Th. List > df-ni | GIF version |
Description: Define the class of positive integers. This is a "temporary" set used in the construction of complex numbers, and is intended to be used only by the construction. (Contributed by NM, 15-Aug-1995.) |
Ref | Expression |
---|---|
df-ni | ⊢ N = (𝜔 ∖ {∅}) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | cnpi 6256 | . 2 class N | |
2 | com 4256 | . . 3 class 𝜔 | |
3 | c0 3218 | . . . 4 class ∅ | |
4 | 3 | csn 3367 | . . 3 class {∅} |
5 | 2, 4 | cdif 2908 | . 2 class (𝜔 ∖ {∅}) |
6 | 1, 5 | wceq 1242 | 1 wff N = (𝜔 ∖ {∅}) |
Colors of variables: wff set class |
This definition is referenced by: elni 6292 pinn 6293 niex 6296 dmaddpi 6309 dmmulpi 6310 |
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