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Mirrors > Home > ILE Home > Th. List > df-xr | Unicode version |
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.) |
Ref | Expression |
---|---|
df-xr |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | cxr 7940 | . 2 | |
2 | cr 7760 | . . 3 | |
3 | cpnf 7938 | . . . 4 | |
4 | cmnf 7939 | . . . 4 | |
5 | 3, 4 | cpr 3582 | . . 3 |
6 | 2, 5 | cun 3119 | . 2 |
7 | 1, 6 | wceq 1348 | 1 |
Colors of variables: wff set class |
This definition is referenced by: ressxr 7950 pnfxr 7959 mnfxr 7963 ltrelxr 7967 elxr 9720 xrex 9800 |
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