Some algebro-geometric aspects of biparametric and coloured quantum groups

Deepak Parashar
Max Planck Institute for Mathematics, Bonn

We investigate some essential algebraic as well as geometric structures
underlying biparametric and coloured quantum groups. GL(2) is known to
admit two distinct quantisations: the standard GL_q(2) and the Jordanian
GL_h(2). The same is true for their respective biparametric versions
GL_p,q(2) and GL_h,h'(2). Though distinct, both these deformations
are related to each other by means of a contraction procedure. There
exists a particularly interesting biparametric quantum deformation of
GL(2) x GL(1) which provides a realization of GL_p,q(2), and also relates
several other examples of quantum groups in a coherent way. We contract
this deformation to obtain its Jordanian analogue which also provides a
realization of GL_h,h'(2) in a manner similar to the q-deformed case. The
scheme is then set in the wider context of `coloured extensions' of
quantum groups. Focussing on the most intuitive example of GL_q(2), I
will present basic results from the theory of coloured quantum groups such
as establishing the picture of duality between the quantised algebra of
functions on a group and the quantised universal enveloping algebra,
constructing differential calculi on these structures within the framework
of the R-matrix approach. The quantum plane covariant under the action of
coloured GL_q(2) will also be exhibited.


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