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Definition df-xr 10116
Description: Define the set of extended reals that includes plus and minus infinity. Definition 12-3.1 of [Gleason] p. 173. (Contributed by NM, 13-Oct-2005.)
Assertion
Ref Expression
df-xr * = (ℝ ∪ {+∞, -∞})

Detailed syntax breakdown of Definition df-xr
StepHypRef Expression
1 cxr 10111 . 2 class *
2 cr 9973 . . 3 class
3 cpnf 10109 . . . 4 class +∞
4 cmnf 10110 . . . 4 class -∞
53, 4cpr 4212 . . 3 class {+∞, -∞}
62, 5cun 3605 . 2 class (ℝ ∪ {+∞, -∞})
71, 6wceq 1523 1 wff * = (ℝ ∪ {+∞, -∞})
Colors of variables: wff setvar class
This definition is referenced by:  ressxr  10121  pnfxr  10130  mnfxr  10134  ltrelxr  10137  ssxr  10145  xrex  11867  elxr  11988  climxlim2lem  40389
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