Elliptic Curves over the Rational Field

New features:

• The improved bound (due to Samir Siksek) on the difference between the naive and canonical heights of a point has been implemented. This bound is now used internally for the group closure operation and is accessible via SiksekBound.

• The Cremona database of elliptic curves now includes all curves of conductor up to 20 000.

Bug fixes:

• A long-standing bug in the 2-descent for certain curves has been fixed. Up to conductor 10 000 there were 14 curves affected, the smallest being 903B3.