**Date & Time:** Friday, September 7, 2012, 16:30-17:30.

**Venue:** Room No. 216 (Mathematics Dept. 2nd Floor)

**Title:**Nice group structure on relative orbit space of unimodular rows.

**Speaker:** Prof. Anuradha Garge,
CBS Mumbai.

**Abstract:**The orbit space of unimodular rows under the action of the
elementary subgroup of the general linear group admits a group structure
depending on the dimension of the ring and the length of unimodular
rows. This group structure was first defined by Vaserstein in case of
length 3 and extended inductively by van der Kallen to length greater
than 3. The formula for this group structure is complicated.

That the group structure has a simpler and ``nicer'' formula depending on the ring and its dimension was shown in the absolute case. These results are extended to the relative case too. This is joint work with Ravi Rao.