Magma V2.15-4 Patch Notes

Algebraic Curves¶

• IsNodal checks for plane curves have been corrected to work for (geometrically) non-reduced curves. Bug reported by A. Brumer.
• The Genus crash over finite fields has been fixed (see note in the Matrices section above).

Arithmetic Geometry¶

• A bug with EisensteinProjection of a modular form that was already in an EisensteinSubspace has been fixed.

Commutative Algebra¶

• A crash in primary decomposition of positive dimensional ideals has been fixed.
• A hang in Groebner basis computation for ideals over GF(2) with a large number of variables has been fixed. Reported by J. Erickson.

Galois Groups¶

• The computation of Galois Groups over function fields of positive characteristic has been switched off due to too many problems. A rewrite is in progress.

Group Representations¶

• When dealing with a natural permutation module of a permutation group, the map returned by the Representation function now uses methods equivalent to using PermutationMatrix rather than using generic group homomorphism methods. Suggested by Markus Grassl.

Groups¶

• A trap for large cyclic components has been installed in the FPGroup function for groups of type GrpAb. Reported by Eamonn O'Brien.
• A crash which occurred when constructing the maximal subgroups of L(10, 2) has been fixed. Reported by Colva Roney-Dougal.
• A bug in filtering subgroups produced by the Subgroups function when the new method for expanding maximal subgroups is used has been fixed. Bug reported by Florian Moeller.

Matrices¶

• A bug involving matrices of polynomials over finite fields (coming out of calls to Genus) has been fixed. Reported by A. Brumer.