Change log for Magma V2.18-11 (Released 5/10/2012)

Abelian Fields

·MaximalOrder of an abelian field has been fixed when a component contained roots of unity in the top extension. Reported by D. Mayer.

Elliptic Curves

·A problem that caused PointsQI to miss some points has been fixed. Reported by R. Rathbun.

Galois Theory

·A fix has been made to the memory management of straight-line polynomials used in the GaloisGroup computations. Reported by C. Schneider.

Graphs

·Assigning an explicitly empty sequence of edge labels to a graph and then asking for the edge labels could cause a crash. This has been fixed. Reported by A. Kasprzyk.

·The directed graph constructors have been extended to allow sequences of edges to be specified rather than just sets (as was formerly the case).

·Spanning trees now retain vertex labels of the containing graph (edge labels remain unretained for now).

Integer Ring

·Error checking for Binomial has improved.

·A bug which caused binomials to be computed in a very inefficient way in some cases has been fixed.

Modules

·A problem in SymmetricPower over non-fields has been fixed. Reported by T. Wieber.

Number Fields

·Automorphisms of fields of fractions whose basis is different to that of the corresponding number field have been fixed.

Polynomial Rings

·A crash in multivariate factorization over the integers with a large number of variables has been fixed.

·An infinite loop in a certain polynomial factorization over number fields has been fixed. Reported by M. Grassl.

Representation Theory

·A bug in computing the character table of a group using the Dixon-Schneider algorithm has been fixed. The bug could cause the character table returned to be incomplete. Bug reported by I. M. Isaacs.

Schemes

·Construction of subschemes of length 0 ambient schemes has been fixed.