Change log for Magma V2.17-3 (Released 12/1/2011)

Aggregates

·A bug that could cause crashes when iterating through multisets has been fixed. Reported by A. Munemasa.

Commutative Algebra

·An incorrect result in IsFree has been fixed. Reported by C. Quitte.

Finitely-presented Groups

·The epimorphisms returned by the SolubleQuotient and PCGroup intrinsics have been extended to support inverse images.

Galois Groups and Subfields

·A fix has been made to the computation of Subfields of number fields in relative represenation.

·A fix has been made to GaloisSubgroup to use a more efficient invariant.

Global Arithmetic Fields

·The computation of maximal orders of Kummer extensions at critical primes has been improved.

Lie Theory

·A bug in RestrictionMatrix has been fixed. Reported by B. van Geemen.

·A bug in IsSimplyConnected and IsAdjoint for non-semisimple root data has been fixed.

·The function TransversalWds for Coxeter groups has been sped up and renamed to TransversalWords.

·A bug in HighestWeightRepresentation for Lie algebras has been fixed. Reported by A. Previtali.

·Some small issues in the computation of Chevalley bases have been resolved.

·The function IsChevalleyBasis has been improved.

Local Arithmetic Fields

·A problem with overzealous optimization in pSelmerGroup for p-adic fields has been fixed. Reported (and fixed) by N. Bruin.

Matrices

·Rows now correctly sets the universe of the returned sequence if it is empty. Reported by C. Quitte.

·Indexing matrices by sequences now allows the null sequence.

·Exp and Log for matrices of nilpotency resp. unipotency degree p over fields of characteristic p have been fixed. Bug reported by A. Previtali.

Polynomial Rings

·A hang in multivariate factorization over finite fields has been fixed. Reported by T. Fisher.

·A crash in Discriminant for a multivariate polynomial in one variable has been fixed. Reported by C. Quitte.

Schemes

·Normalization of the defining equations of a map into a scheme with a non-trivial grading has been improved to remove common factors. This includes hyperellitpic curve and ambients thereof as codomains.

Series Rings

·Finding mulitple roots of polynomials over series rings has been improved.

·Reversion of a series whose coefficient ring is not a field has been disallowed.