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| Mirrors > Home > MPE Home > Th. List > df-ni | Structured version Visualization version GIF version | ||
| Description: Define the class of positive integers. This is a "temporary" set used in the construction of complex numbers df-c 11161, and is intended to be used only by the construction. (Contributed by NM, 15-Aug-1995.) (New usage is discouraged.) |
| Ref | Expression |
|---|---|
| df-ni | ⊢ N = (ω ∖ {∅}) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | cnpi 10884 | . 2 class N | |
| 2 | com 7887 | . . 3 class ω | |
| 3 | c0 4333 | . . . 4 class ∅ | |
| 4 | 3 | csn 4626 | . . 3 class {∅} |
| 5 | 2, 4 | cdif 3948 | . 2 class (ω ∖ {∅}) |
| 6 | 1, 5 | wceq 1540 | 1 wff N = (ω ∖ {∅}) |
| Colors of variables: wff setvar class |
| This definition is referenced by: elni 10916 pinn 10918 niex 10921 ltsopi 10928 dmaddpi 10930 dmmulpi 10931 wuncn 11210 |
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