#18660: Improve efficiency of minors() for BinaryMatroid, TernaryMatroid,
QuaternaryMatroid
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Reporter: Rudi | Owner: Rudi
Type: task | Status: new
Priority: major | Milestone: sage-6.8
Component: matroid theory | Keywords:
Merged in: | Authors:
Reviewers: | Report Upstream: N/A
Work issues: | Branch:
Commit: | Dependencies:
Stopgaps: |
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The representing matrices of BinaryMatroid, TernaryMatroid,
QuaternaryMatroid, are bitpacket. Taking minors, involves constructing a
submatrix of such a representing matrix. Since the rows are bitpacked, the
relocation of columns in particular is relatively inefficient.
By allowing a submatrix in which the columns are allowed to be permuted,
it is possible to reduce the number of column relocations to at most the
number of deleted columns, and this will be far more efficient than the
current implementation, especially if few columns are deleted.
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Ticket URL: <http://trac.sagemath.org/ticket/18660>
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