1. CMB 2009 (vol 40 pp. 352)
||A New Proof of a Theorem of Magnus |
Using naive algebraic geometric methods a new proof of the
following celebrated theorem of Magnus is given:
Let $G$ be a group with a presentation having $n$ generators and $m$
relations. If $G$ also has a presentation on $n-m$ generators, then
$G$ is free of rank $n-m$.
Categories:20E05, 20C99, 14Q99
2. CMB 2008 (vol 51 pp. 125)
||Explicit Real Cubic Surfaces |
The topological classification of smooth real
cubic surfaces is
recalled and compared to the classification in terms of
the number of real lines and of real tritangent planes,
by L.~Schl\"afli in 1858.
Using this, explicit examples of
surfaces of every possible type are given.
Categories:14J25, 14J80, 14P25, 14Q10