Change log for Magma V2.25-6 (Released 24/7/2020)

Finite Fields

·The default strategy for selecting the Pohlig-Hellman discrete logarithm algorithm has been improved for finite fields. Also, if K is a finite field, one may now set the attribute K'UsePHLog (with the backquote operator) to whether the Pohlig-Hellman will be used when computing logarithms in K. Issue reported by J. Jean.

Galois Theory

·A recently introduced bug in the intrinsic SolveByRadicals for polynomials over the rational field has been fixed.

Groebner Bases

·A crash when computing large Groebner bases over non-prime finite fields of characteristic 2 has been fixed. The F4 algorithm for such inputs in the sparse case has been improved also. Reported by D. Craven.

·Incorrect sign handling when computing coordinates of polynomial/vectors in ideals/modules defined over exterior algebras has been fixed. Reported by M. Barakat.

·A missing error check for noncommutative Groebner basis computation over unsupported rings has been added. Reported by R. Bruner.

Group Theory

·Operations involving sets of permutation groups no longer compute a minimal set of generators, which should make them faster in almost all cases.

·A crash in p-group generation (for example, intrinsics GeneratepGroups and Descendants), caused by a subtle limit in the Magma memory manager has been fixed. Reported by M. Newman.

Lattices

·Setting one of the attribues Minimum, Kissing Number, or Theta Series when one of the other attributes is set will no longer print the theta series.

Local Fields

·A bug in the construction of a local field which is not a scalar multiple of a monic integral polynomial has been fixed. Reported by S. Marseglia.

Matrices

·A bug when computing the determinant of matrices over polynomial rings over non-domains has been fixed. Reported by J. Voight.

Number Fields

·Computing primes in the discriminant of an order whilst computing a MaximalOrder has been improved by using the Smith form of the trace matrix.

·A bug has been fixed in the computation of maximal orders using the Discriminant and Ramification parameters. Reported by J. KlÃ¼ners.

·A bug in coercion of elements in large towers has been fixed. Reported by M. Grassl.

·In the construction an AbelianExtension of a number field, additional checking has been added to ensure that extensions arising are both normal and abelian. Reported by M. Grassl.

Polynomial Rings

·A bug in Normalize for univariate polynomials defined over integer residue class rings has been fixed, so the result is guaranteed to be unique. Reported by L. Notarfrancesco.

·The check for overflow in the number of monomials in a multivariate polynomial ring was not quite correct and has been fixed. Reported by T. Verron.

Quaternion Algebras

·A bug when computing of the discriminant of a quaternion algebra has been fixed by J. Voight. Reported by M. Schein.

Schemes

·A crash in IsInvertible applied to a map between schemes when the parameter Maximal is set to true has been fixed. Reported by N. Bruin.

System

·Power structures may now be compared and placed in sets.

Toric Varieties

·Maps involving Toric Varieties have been improved. Reported by A. Laface.