  We propose a new approach to the multiplication of Schubert classes in the
K-theory of the flag variety. This extends the work of Fomin and Kirillov in
the cohomology case, and is based on the quadratic algebra defined by them.
More precisely, we define K-theoretic versions of the Dunkl elements considered
by Fomin and Kirillov, show that they commute, and use them to describe the
structure constants of the K-theory of the flag variety with respect to its
basis of Schubert classes.
