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Implement Orlik-Solomon algebra of an arrangement #18133

Closed kcrisman closed 8 years ago

kcrisman commented 9 years ago

The Orlik-Solomon algebra is a fundamental invariant for an arrangement, which also enables computing scads of useful information about e.g. the complement. But it's purely algebraic. So we should have it (see also #17506).

CC: @tscrim @sagetrac-Stefan @sagetrac-yomcat @chaoxu

Component: geometry

Keywords: hyperplane arrangements

Author: Travis Scrimshaw, William Slofstra

Branch/Commit: 48e46b6

Reviewer: Darij Grinberg

Issue created by migration from https://trac.sagemath.org/ticket/18133

darijgr commented 8 years ago
comment:33

Perfect!

vbraun commented 8 years ago
comment:34
sage -t --long src/sage/matroids/matroid.pyx
**********************************************************************
File "src/sage/matroids/matroid.pyx", line 2912, in sage.matroids.matroid.Matroid.orlik_solomon_algebra
Failed example:
    OS = M.orlik_solomon_algebra(QQ)
Expected:
    Orlik-Solomon algebra of U(3, 4): Matroid of rank 3 on 4 elements
     with circuit-closures
     {3: {{0, 1, 2, 3}}}
Got:
    <BLANKLINE>
**********************************************************************
1 item had failures:
   1 of   3 in sage.matroids.matroid.Matroid.orlik_solomon_algebra
    [775 tests, 1 failure, 2.64 s]
7ed8c4ca-6d56-4ae9-953a-41e42b4ed313 commented 8 years ago

Changed commit from ce4a0cb to 48e46b6

7ed8c4ca-6d56-4ae9-953a-41e42b4ed313 commented 8 years ago

Branch pushed to git repo; I updated commit sha1. New commits:

48e46b6Fixing trivial doctest failure.
tscrim commented 8 years ago
comment:36

Stupid me; trivial doctest fix.

darijgr commented 8 years ago
comment:37

Oops, that was me being stupid too. The only file I've run the tests on was orlik-solomon.py...

vbraun commented 8 years ago

Changed branch from public/algebras/orlik_solomon-18133 to 48e46b6