#11506: Fix the infinity ring.
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       Reporter:  vbraun             |        Owner:  AlexGhitza
           Type:  defect             |       Status:  needs_info
       Priority:  blocker            |    Milestone:  sage-6.3
      Component:  algebra            |   Resolution:
       Keywords:                     |    Merged in:
        Authors:  Volker Braun       |    Reviewers:  Peter Bruin
Report Upstream:  N/A                |  Work issues:
         Branch:                     |       Commit:
  u/vbraun/infinity_ring             |  3531287276d95f0a60b762c4dc5475bee4860cba
   Dependencies:  #13125             |     Stopgaps:
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Comment (by pbruin):

 Replying to [comment:37 tscrim]:
 > So IMO it still is a field (it also is in the category of `Fields`)
 `RIF` is definitely not a field (and neither are `RR` and `RDF`).  They
 are Sage objects that approximate the field '''R''' of real numbers in
 different ways, but none of these Sage objects satisfies the axioms of a
 field.
 > Now the infinity ring is a actually a semiring, but nevertheless it
 still has less structure.
 I don't understand this.  Addition of `+Infinity` and `-Infinity` is
 undefined in the infinity ring, or is this what you mean by "less
 structure"?
 > Even if we don't want to consider which category, the basic promise of
 coercion is that if you can do operation `#` on (2 elements of) `A`, then
 you can do the same (equivalent?) operation on `B`.
 No, the operation `4 // 2` is defined in `ZZ`, but not after coercion to
 `Zmod(8)`, for example.

--
Ticket URL: <http://trac.sagemath.org/ticket/11506#comment:38>
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