#19473: FiniteDimensionalAlgebra.is_unitary is not sufficient
-------------------------------------+-------------------------------------
Reporter: darij | Owner:
Type: defect | Status: needs_review
Priority: major | Milestone: sage-6.10
Component: algebra | Resolution:
Keywords: finite- | Merged in:
dimensional algebra, linear | Reviewers: Travis Scrimshaw
algebra | Work issues: clear up
Authors: Darij Grinberg, | associativity requirement; if
Travis Scrimshaw | necessary, change superclass and
Report Upstream: N/A | is_unitary method
Branch: | Commit:
public/algebra/finite_dim_algebra_fixes-19473|
0cfe0366fc527d2f692c835be3d40f60aa61c471
Dependencies: | Stopgaps:
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Comment (by pbruin):
Replying to [comment:18 darij]:
> Johan Bosman's approach looks correct (mathematically -- haven't checked
the programming). It isn't even necessary to check that the two identities
are equal, since their existence already yields their equality.
Indeed, I have now also convinced myself of this. This means that we can
replace
{{{
#!python
if sol1 == sol2:
self._one = sol1
return True
else:
return False
}}}
by
{{{
#!python
assert sol1 == sol2
return True
}}}
(note that at this point the fact that `sol1` and `sol2` have been
computed implies that left and right identity elements exist).
--
Ticket URL: <http://trac.sagemath.org/ticket/19473#comment:19>
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