Change log for Magma V2.26-6 (Released 6/8/2021)

Algebraically Closed Fields

·A crash in the Roots function for polynomials defined over algebraically closed fields defined over function fields of small characteristic has been fixed. Reported by L. Voggesberger.

Commutative Algebra

·The function MinimalBasis for an ideal of a multivariate polynomial ring has been improved in the search for a grading to make the input homogeneous if it is not already. The new function HomogeneousWeightsSearch also does the search for weights. Issue reported by A. Laface.

Elliptic Curves

·A possible crash in RankBounds of an elliptic curve over a number field has been fixed. Reported by L. Halbeisen.

Exact $p$-adic Rings and Fields

·Documentation for the C version of Christopher Doris's package for exact arithmetic in p-adic rings and fields has been included as the last section of the chapter on p-adic Rings.

Exterior Algebras

·A bug in ChangeRing for exterior algebras has been fixed. Reported by E. Campbell.

Finite Groups

·A minor printing bug in character tables has been fixed. This bug could cause column widths to be too small by a character, causing some entries in those columns to directly abut entries from the previous column.

Hyperelliptic Curves

·A bug has been fixed that could cause random data to be printed in an error message when coercion into a Jacobian failed. Reported by M. Stoll and T. Keller.

Matrix Groups

·This upgrade distributes the first complete version of a new package to list conjugacy classes, determine centralisers, and decide conjugacy in natural copies of the classical groups. The Classes intrinsic uses this machinery by default to compute classes. The other intrinsics include ClassicalIsConjugate, ClassicalCentraliser, ClassicalClassMap, ClassesForFixedSemisimple and IsometryGroupClassLabel. The package incorporates code developed by Giovanni de Franceschi, and was prepared by Eamonn O'Brien and Don Taylor.

·The function ClassicalGroupType builds on ClassicalType and returns the precise type of a natural copy of a classical group. This was prepared by Eamonn O'Brien and Don Taylor.

Module Theory

·A slowdown when deleting large sequences of G-modules has been fixed. Reported by E. O'Brien.

Object Transmission

·A bug with receiving matrix types inside tuples has been fixed. Reported by M. Kirschmer.

Sequences

·Applying &cat to sequences of strings (or binary strings) with undefined elements now gives an error instead of crashing. Reported by A. Munemasa.