Magma V2.11-13 Patch Notes

Algebras¶

• A bug in the map for Algebra of a matrix algebra has been fixed.

Commutative Algebra¶

• A bug causing a bad slowdown when computing Gröbner bases over $GF(2)$ with field polynomials (non-HFE) has been fixed.

Groups¶

• A bug with the construction of stabilizer subgroups of matrix groups has been fixed. This caused a crash in V2.11-12 (but not earlier versions) when BSGS or Verify was used on these subgroups. Bug reported by Markus Grassl.
• The order of a matrix group with a single generator is now determined by the order of the generator rather than by STCS. Suggested by Derek Holt.
• Matrix group STCS has been modified to add extra strong generators to force shallow schreier trees (much as the random schreier does). This will hasten membership testing and homomorphism evaluation, and may improve STCS performance along the way.
• A matrix group bug which sometimes caused GModule and ChiefSeries to go into an infinite loop has been fixed.

Number Fields¶

• A problem with the coercion of elements of real quadratic elements into the fixed precision reals has been fixed. The bug was causing Magma internal errors.
• A bug in the arithmetic of extensions of non-simple number fields has been fixed. This bug was causing wrong results.

Polynomial Rings¶

• IsUnit and inversion for elements of polynomial quotient rings over prime-power residue rings are now supported properly.

System and Language¶

• A bug involving print levels in packages has been fixed.