Definition df-ni 10957

Description: Define the class of positive integers. This is a "temporary" set used in the construction of complex numbers df-c 11206, and is intended to be used only by the construction. (Contributed by NM, 15-Aug-1995.) (New usage is discouraged.)

Assertion

Ref	Expression
df-ni	⊢ N = (ω ∖ {∅})

Detailed syntax breakdown of Definition df-ni

Step	Hyp	Ref	Expression
1		cnpi 10929	. 2 class N
2		com 7877	. . 3 class ω
3		c0 4278	. . . 4 class ∅
4	3	csn 4583	. . 3 class {∅}
5	2, 4	cdif 4045	. 2 class (ω ∖ {∅})
6	1, 5	wceq 1569	1 wff N = (ω ∖ {∅})

This definition is used by:  elni  10961  pinn  10963  niex  10966  ltsopi  10973  dmaddpi  10975  dmmulpi  10976  wuncn  11255