Definition df-ni 7305

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. = ( om \ { (/) } )

Detailed syntax breakdown of Definition df-ni

Step	Hyp	Ref	Expression
1		cnpi 7273	. 2 class N.
2		com 4591	. . 3 class om
3		c0 3424	. . . 4 class (/)
4	3	csn 3594	. . 3 class { (/) }
5	2, 4	cdif 3128	. 2 class ( om \ { (/) } )
6	1, 5	wceq 1353	1 wff N. = ( om \ { (/) } )

This definition is referenced by:  elni  7309  pinn  7310  niex  7313  dmaddpi  7326  dmmulpi  7327