#5125: Ideal.basis_is_groebner() may return wrong results
---------------------------------+------------------------------------------
Reporter: malb | Owner: malb
Type: defect | Status: new
Priority: critical | Milestone: sage-3.3
Component: commutative algebra | Keywords:
---------------------------------+------------------------------------------
For the attached list, {{{Ideal(gb).basis_is_groebner()}}} returns
{{{True}}} but the basis is not a Gröbner basis!
The code in question:
{{{
def basis_is_groebner(self, singular=singular_default):
self.ring()._singular_().set_ring()
F = singular( self.gens(), "module" )
LTF = singular( [f.lt() for f in self.gens()] , "module" )
M = (F * LTF.syz()).reduce(self._singular_())
for i in range(M.nrows()):
if int(singular.eval("%s[1][%s+1]!=0"%(M.name(),i))):
return False
self._singular_().attrib('isSB',1)
return True
}}}
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/5125>
Sage <http://sagemath.org/>
Sage - Open Source Mathematical Software: Building the Car Instead of
Reinventing the Wheel
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"sage-trac" group.
To post to this group, send email to [email protected]
To unsubscribe from this group, send email to
[email protected]
For more options, visit this group at
http://groups.google.com/group/sage-trac?hl=en
-~----------~----~----~----~------~----~------~--~---
