### From Mennicke symbols to Euler class groups, by Wilberd van der Kallen

This is an expanded version of a talk given in January 2000 at the
International Colloquium at TIFR. We discuss an exact sequence of pointed
sets. The last map in the sequence is the homomorphism of Bhatwadekar and
Raja Sridharan from an orbit set of unimodular rows of length d+1 to their
Euler class group for rank d projective modules. Here d is the dimension of a
commutative ring containing the rational numbers.

Wilberd van der Kallen <vdkallen@math.uu.nl>