#11309: Sage sees - x + y > 0, - y + x >= 0, and x - y > 0 as equivalent
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Reporter: tnv |
Owner: burcin
Type: defect |
Status: positive_review
Priority: major |
Milestone: sage-5.1
Component: symbolics |
Resolution:
Keywords: inequality equality relational sd31 __richcmp__ sd40.5 |
Work issues:
Report Upstream: N/A |
Reviewers: Karl-Dieter Crisman, ThanhVu Nguyen
Authors: Keshav Kini, Burcin Erocal |
Merged in:
Dependencies: |
Stopgaps:
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Comment (by kini):
Given two relations `a ? b` and `c ! d`, first I check whether `?` and `!`
are the same relation. If so, I have a couple of cases. One, if `?` and
`!` are both `==` or are both `!=`, then I check whether `a == c` and `b
== d`, or `a == d` and `b == c`. Two, if `?` and `!` are some other
relation than `==` or `!=`, then I only allow the case `a == c` and `b ==
d`.
If `?` and `!` are different from each other, I check whether they are
reversals of each other (like one is `<` and the other is `>`, etc.). If
that is the case, then I allow `a == d` and `b == c`.
In all other cases, the two relations are disallowed.
... that explanation looks kind of confusing. Maybe it's better if you
just look at the patch... it's probably easier to understand :)
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11309#comment:57>
Sage <http://www.sagemath.org>
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