#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 tscrim):

 There should be a bit better check of equality in RIF as `x - x` will be 0
 because we know we are subtracting the same number (even if we don't know
 the exact number). However `RIF(0,1) - RIF(0,1)` may or may not be 0, we
 don't know because the left and right terms may or may not be the same
 value. So IMO it still is a field (it also is in the category of
 `Fields`), but doing exact comparisons can be difficult.

 Now the infinity ring is a actually a semiring, but nevertheless it still
 has 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`.

--
Ticket URL: <http://trac.sagemath.org/ticket/11506#comment:37>
Sage <http://www.sagemath.org>
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