Opened 4 years ago

Last modified 4 years ago

#18902 new defect

spurious results as inequality solution

Reported by: rws Owned by:
Priority: major Milestone: sage-6.8
Component: symbolics Keywords:
Cc: Merged in:
Authors: Reviewers:
Report Upstream: N/A Work issues:
Branch: Commit:
Dependencies: Stopgaps:

Description (last modified by rws)

From, http://ask.sagemath.org/question/26941/solving-system-of-inequalities-in-one-variable/:

x = var('x')
a = var('a')
solve([a*x>0,a>0],[x])
[[0 < x, a > 0], [x < 0, -a > 0, a > 0]]

The second solution contradicts one given precondition.

Also, from http://ask.sagemath.org/question/26410/test-if-an-inequality-is-feasible-under-assumptions/

sage: (l1,l2) = var("l1 l2")
sage: assume (l1>=0)
sage: assume (l2>=0)
sage: solve (l1*l2<0, [l1,l2])
[[0 < l2, l1 < 0], [l2 < 0, 0 < l1]]

Change History (1)

comment:1 Changed 4 years ago by rws

  • Description modified (diff)
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