Definition df-mnf 7156

Description: Define minus infinity as the power set of plus infinity. Note that the definition is arbitrary, requiring only that -oo be a set not in RR and different from +oo (see mnfnre 7161). (Contributed by NM, 13-Oct-2005.) (New usage is discouraged.)

Assertion

Ref	Expression
df-mnf	|- -oo = ~P +oo

Detailed syntax breakdown of Definition df-mnf

Step	Hyp	Ref	Expression
1		cmnf 7151	. 2 class -oo
2		cpnf 7150	. . 3 class +oo
3	2	cpw 3382	. 2 class ~P +oo
4	1, 3	wceq 1284	1 wff -oo = ~P +oo

This definition is referenced by:  mnfnre  7161  mnfxr  8848  pnfnemnf  8851