Opened 9 years ago

Last modified 7 years ago

#11309 closed defect

Sage sees -x +y > 0, -y + x >= 0, and x -y > 0 as equivalent — at Version 3

Reported by: tnv Owned by: burcin
Priority: major Milestone: sage-5.1
Component: symbolics Keywords: inequality equality relational sd31 __richcmp__ sd40.5
Cc: kini, kcrisman, tnv Merged in:
Authors: Reviewers:
Report Upstream: N/A Work issues:
Branch: Commit:
Dependencies: Stopgaps:

Description (last modified by kini)

-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 >, >=, and == the same (see #7660). If this is true then it's a serious problem and needs to be addressed.

Change History (3)

comment:1 Changed 9 years ago by tnv

  • Description modified (diff)

comment:2 Changed 9 years ago by kini

  • Cc kini added

comment:3 Changed 8 years ago by kini

  • Description modified (diff)
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