Opened 12 years ago
Closed 12 years ago
#6669 closed defect (fixed)
Homomorphisms from matrix groups don't have to have matrix groups as codomain
Reported by: | mraum | Owned by: | mraum |
---|---|---|---|
Priority: | major | Milestone: | sage-4.3 |
Component: | coercion | Keywords: | |
Cc: | mhansen, AlexGhitza | Merged in: | sage-4.3.alpha0 |
Authors: | Martin Raum | Reviewers: | Robert Bradshaw |
Report Upstream: | Work issues: | add doctests | |
Branch: | Commit: | ||
Dependencies: | Stopgaps: |
Description
This is an error which occurs if one tries to construct coercing from a matrix group into an algebra. The current implementation of homomorphisms with domain a matrix group require the codomain to be a matrix group, too.
/home/martin/sage-4.1_compiled/local/lib/python2.6/site-packages/sage/categories/homset.pyc in Hom(X, Y, cat) 64 """ 65 if hasattr(X, '_Hom_'): ---> 66 return X._Hom_(Y, cat) 67 68 global _cache /home/martin/sage-4.1_compiled/local/lib/python2.6/site-packages/sage/groups/matrix_gps/matrix_group.pyc in _Hom_(self, G, cat) 230 raise NotImplementedError 231 if not is_MatrixGroup(G): --> 232 raise TypeError, "G (=%s) must be a matrix group."%G 233 import homset 234 return homset.MatrixGroupHomset(self, G) TypeError: G (=Group algebra of group "General Linear Group of degree 3 over Finite Field of size 7" over base ring Integer Ring) must be a matrix group.
Attachments (2)
Change History (9)
Changed 12 years ago by
comment:1 Changed 12 years ago by
- Status changed from new to needs_review
- Summary changed from Homomorphisms from matrix groups don't have to have matrix groups as codomain to [with patch, needs review]Homomorphisms from matrix groups don't have to have matrix groups as codomain
comment:2 Changed 12 years ago by
- Cc mhansen added
comment:3 Changed 12 years ago by
- Cc AlexGhitza added
- Summary changed from [with patch, needs review]Homomorphisms from matrix groups don't have to have matrix groups as codomain to Homomorphisms from matrix groups don't have to have matrix groups as codomain
comment:4 Changed 12 years ago by
- Status changed from needs_review to needs_work
- Work issues set to add doctests
comment:5 Changed 12 years ago by
- Status changed from needs_work to needs_review
Yep, doctests look fine.
comment:6 Changed 12 years ago by
- Status changed from needs_review to positive_review
Looks good to me.
comment:7 Changed 12 years ago by
- Merged in set to sage-4.3.alpha0
- Resolution set to fixed
- Reviewers set to Robert Bradshaw
- Status changed from positive_review to closed
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This looks good, applies cleanly and passes long tests under sage-4.2. I will test on sage-4.2.1 as soon as sage.math binaries are available.
One thing needs to be fixed: please add some doctests with examples of homomorphisms between matrix groups, and from matrix groups to other types of groups. (I do realise that the method patched here did not have doctests to start with.)