Change log for Magma V2.19-9 (Released 28/8/2013)

Aggregates

·A crash in the reduction operator &* on isets has been fixed. Reported by G. Williamson.

Algebraic Function Fields

·Improvements have been made to some computations of GaloisGroup.

·CoveringStructure has been refined for sets of ideals of orders of function fields. In particular, there is no covering structure for a set of ideals of a finite order and a set of ideals of an infinite order. Reported by I. Pirsic.

·StrongApproximation has been improved to better handle input of zero. Reported by I. Pirsic.

Algebraic Number Fields

·Memory management has been improved in one place of the class group computation.

·Error checking has been improved so that PrimitiveElement can only be computed for ideals of maximal orders.

Coding Theory

·Determining the weight distribution of a code that is known to be MDS would sometimes work via the dual code instead. This has been fixed.

Complex Numbers

·A crash in RootsNonExact where zero is a root of the polynomial has been fixed. Reported by P. Yatsyna.

Elliptic Curves

·A bug in the EllipticCurve intrinsic that produced deeply embedded rather than top-level runtime errors has been fixed. Reported by M. Zieve.

Finitely Presented Algebras

·A crash when computing the Groebner basis of some finitely presented algebras has been fixed. Reported by D. Simpson.

Groups

·Long relators in the input to RWSGroup have been trapped before they cause memory problems by exceeding MaxReduceLen. Bug reported by Derek Holt.

·A new intrinsic TableOfMarks has been installed. This may be applied to sufficiently small permutation groups and pc-groups to get Burnside's table of marks for the group. The algorithm first computes the lattice of subgroup classes of the group.

·This update contains a new implementation of the black box recognition algorithm of Beals et al for alternating and symmetric groups by Jonathan Conder. This is accessed using the intrinsic function RecogniseAlternatingOrSymmetric, which now has different return values to the previous version. If the algorithm succeeds when given input group G, then G is isomorphic to H which is either alternating or symmetric. In this case it returns true, an isomorphism from G to H, an isomorphism from H to G, the map from G to its word group, and the map from the word group to G. The sixth value returned is true if H is the symmetric group, otherwise false. If the algorithm fails, then the first and only return value is false, the remaining 5 possible return values are unassigned.

LSeries

·A TensorProduct now inherits the minimal precision of its constituent parts.

Local Rings and Fields

·Factorization of polynomials over local rings and fields with the Extensions parameter set to true has been fixed. Reported by T. Dokchitser.

Modules over Dedekind Domains

·IsZero is now provided for elements of modules over Dedekind domains. Reported by M. Kirschmer.

Orders of Associative Algebras

·Memory management in the powering of elements has been fixed.

Polytopes and Polyhedra

·The new intrinsic VertexEdgeIncidenceMatrix can be used to recover the vertex-edge incidence matrix of a polyhedron.

Vector Spaces

·Some problems with generators in the procedural versions of Include have been fixed.