Definition df-xr 5643

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 5639	. 2 class RR*
2		cr 5387	. . 3 class RR
3		cpnf 5637	. . . 4 class +oo
4		cmnf 5638	. . . 4 class -oo
5	3, 4	cpr 2468	. . 3 class { +oo, -oo}
6	2, 5	cun 2097	. 2 class (RR u. { +oo, -oo})
7	1, 6	wceq 992	1 wff RR* = (RR u. { +oo, -oo})

This definition is referenced by:  xrex 5646  pnfxr 5647  mnfxr 5648  ressxr 5652  elxr 5689  ssxr 5694

Copyright terms: Public domain