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Definition df-xr 10366
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 10361 . 2 class *
2 cr 10223 . . 3 class
3 cpnf 10359 . . . 4 class +∞
4 cmnf 10360 . . . 4 class -∞
53, 4cpr 4379 . . 3 class {+∞, -∞}
62, 5cun 3774 . 2 class (ℝ ∪ {+∞, -∞})
71, 6wceq 1637 1 wff * = (ℝ ∪ {+∞, -∞})
Colors of variables: wff setvar class
This definition is referenced by:  ressxr  10371  pnfxr  10380  mnfxr  10384  ltrelxr  10387  ssxr  10395  xrex  12046  elxr  12169  climxlim2lem  40552
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