Definition df-ni 10674

Description: Define the class of positive integers. This is a "temporary" set used in the construction of complex numbers df-c 10923, 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 10646	. 2 class N
2		com 7744	. . 3 class ω
3		c0 4262	. . . 4 class ∅
4	3	csn 4565	. . 3 class {∅}
5	2, 4	cdif 3889	. 2 class (ω ∖ {∅})
6	1, 5	wceq 1539	1 wff N = (ω ∖ {∅})

This definition is referenced by:  elni  10678  pinn  10680  niex  10683  ltsopi  10690  dmaddpi  10692  dmmulpi  10693  wuncn  10972