Definition df-xr 6656

Description: Define the set of extended reals that includes plus and minus infinity. Definition 12-3.1 of [Gleason] p. 173.

Assertion

Ref	Expression
df-xr	|- RR* = (RR u. { +oo, -oo})

Detailed syntax breakdown of Definition df-xr

Step	Hyp	Ref	Expression
1		cxr 6652	. 2 class RR*
2		cr 6385	. . 3 class RR
3		cpnf 6650	. . . 4 class +oo
4		cmnf 6651	. . . 4 class -oo
5	3, 4	cpr 3045	. . 3 class { +oo, -oo}
6	2, 5	cun 2591	. 2 class (RR u. { +oo, -oo})
7	1, 6	wceq 1298	1 wff RR* = (RR u. { +oo, -oo})

This definition is referenced by:  xrex 6659  pnfxr 6660  pnfxrOLD 6661  mnfxr 6662  mnfxrOLD 6663  ressxr 6667  elxr 6706  ssxr 6714  ssxrOLD 6715

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