LinearMatroid.has_line_minor should catch NotImplementedError

[sagetrac-Stefan]

The following code should not throw an error:

sage: R.<x,y> = ZZ['x','y']
sage: Q = R.quotient([x^2 - y + 1, y^3 + 3 * x - 7])
sage: M = LinearMatroid(ring=Q, reduced_matrix=Matrix([[1,0,1],[0,1,1]]))
sage: M.has_line_minor(3)
Traceback (most recent call last):
...
NotImplementedError:

Easy solution: add NotImplementedError to the except clause in the code.

Component: matroid theory

Branch/Commit: u/Rudi/ticket/15295 @ dd3ad7d

Issue created by migration from https://trac.sagemath.org/ticket/15295

[sagetrac-Rudi]

Branch: u/Rudi/ticket/15295

[sagetrac-Rudi]

Commit: dd3ad7d

[sagetrac-Rudi]

comment:4

Added that exception clause. Now the same example raises another NotImplementedError, but one that gives more information. Essentially, computing ratios in that given ring Q is not possible, which is a problem in LinearMatroid._line_ratios().

So what is the policy here? Should has_line_minor() test if computing inverses is possible before handing the problem down?

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New commits:

dd3ad7d

Added an exception clause to catch a NonImplementedError below LinearMatroid.has_minor()