#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: new
Priority: major | Milestone: sage-4.7.1
Component: symbolics | Keywords: inequality, equality
Work_issues: | Upstream: N/A
Reviewer: | Author:
Merged: | Dependencies:
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Description changed by kini:
Old description:
> -x + y > 0 and x - y > 0 are treated the same in Sage.
>
> {{{
> sage: version()
> 'Sage Version 4.6.2, Release Date: 2011-02-25'
>
> sage: (-x +y < 0) in [x -y < 0]
> True
>
> Set([-x +y >= 0,x -y >= 0])
> {-x + y >= 0}
> }}}
>
> and they have the same Hash
>
> {{{
> sage: var('x,y')
> (x, y)
> sage: hash(-x + y > 0 )
> 1221566266
> sage: hash(-x + y >= 0 )
> 1221566266
> sage: hash(x - y >= 0 )
> 1221566266
> sage: hash(-y + x >= 0 )
> 1221566266
> sage: hash(x - y > 0 )
> 1221566266
> }}}
>
> It seems to me that Sage treats > , >= , == the same (see
> http://trac.sagemath.org/sage_trac/ticket/7660). If this is true then
> it's a serious problem and needs to be addressed.
New description:
-x + y > 0 and x - y > 0 are treated the same in Sage.
{{{
#!python
sage: version()
'Sage Version 4.6.2, Release Date: 2011-02-25'
sage: (-x +y < 0) in [x -y < 0]
True
Set([-x +y >= 0,x -y >= 0])
{-x + y >= 0}
}}}
and they have the same Hash
{{{
#!python
sage: var('x,y')
(x, y)
sage: hash(-x + y > 0 )
1221566266
sage: hash(-x + y >= 0 )
1221566266
sage: hash(x - y >= 0 )
1221566266
sage: hash(-y + x >= 0 )
1221566266
sage: hash(x - y > 0 )
1221566266
}}}
It seems to me that Sage treats `>`, `>=`, and `==` the same (see #7660).
If this is true then it's a serious problem and needs to be addressed.
--
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11309#comment:3>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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