  This is an exposition of some recent developments related to the object in
the title, particularly the combinatorial computation of the (genus 0)
Gromov-Witten invariants of the flag manifold and the quadratic algebra
approach. The notes are largely based on my joint papers with S.Gelfand,
A.N.Kirillov, and A.Postnikov. This is by no means an exhaustive survey of the
subject, but rather a casual introduction to its combinatorial aspects.
