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Definition df-mnf 6860
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 6865). (Contributed by NM, 13-Oct-2005.) (New usage is discouraged.)
Ref Expression
df-mnf -oo  ~P +oo

Detailed syntax breakdown of Definition df-mnf
StepHypRef Expression
1 cmnf 6855 . 2 -oo
2 cpnf 6854 . . 3 +oo
32cpw 3351 . 2  ~P +oo
41, 3wceq 1242 1 -oo  ~P +oo
Colors of variables: wff set class
This definition is referenced by:  mnfnre  6865  mnfxr  8464  pnfnemnf  8467
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