© 1995 by London Mathematical Society
© The London Mathematical Society
The Defining Relations of Quantum n x n Matrices
Department of Mathematics, University of Washington Seattle, Washington 98195, USA
Received 20 October 1993. Revision received 13 January 1994.
Let
q(Mn) denote the coordinate ring of quantum n x n matrices. We show there exists a subvariety
n of P(Mn) and an automorphism
n of
n such that
q(Mn) determines, and is determined by, the geometric data {
n,
n}; the linear span of the defining relations of
q(Mn) is the set of all those elements of
that vanish on the graph of
n. Moreover, if q2
1, the variety
n is independent of q. Our main result is that there are two natural descriptions of
n. Firstly, if q
kx, there is a natural bijection between
n and the point modules over
q(Mn), and the automorphism
n is the shift functor on point modules. Secondly, since
q(Mn) is a graded flat deformation of
1(Mn) the polynomial ring
(Mn), there is a homogeneous Poisson bracket on
(Mn) and an associated Poisson structure on P(Mn). In this context, if q2
1, the variety
n consists of those points of P(Mn) which are the zero-dimensional symplectic leaves with respect to this Poisson structure.
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