Definition df-ni 10909

Description: Define the class of positive integers. This is a "temporary" set used in the construction of complex numbers df-c 11158, 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 10881	. 2 class N
2		com 7886	. . 3 class ω
3		c0 4338	. . . 4 class ∅
4	3	csn 4630	. . 3 class {∅}
5	2, 4	cdif 3959	. 2 class (ω ∖ {∅})
6	1, 5	wceq 1536	1 wff N = (ω ∖ {∅})

This definition is referenced by:  elni  10913  pinn  10915  niex  10918  ltsopi  10925  dmaddpi  10927  dmmulpi  10928  wuncn  11207