Definition df-ni 7517

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.)

Assertion

Ref	Expression
df-ni	⊢ N = (ω ∖ {∅})

Detailed syntax breakdown of Definition df-ni

Step	Hyp	Ref	Expression
1		cnpi 7485	. 2 class N
2		com 4686	. . 3 class ω
3		c0 3492	. . . 4 class ∅
4	3	csn 3667	. . 3 class {∅}
5	2, 4	cdif 3195	. 2 class (ω ∖ {∅})
6	1, 5	wceq 1395	1 wff N = (ω ∖ {∅})

This definition is referenced by:  elni  7521  pinn  7522  niex  7525  dmaddpi  7538  dmmulpi  7539