This book gives an introduction to the very active field of
combinatorics of affine Schubert calculus, explains the current state of
the art, and states the current open problems. Affine Schubert calculus
lies at the crossroads of combinatorics, geometry, and representation
theory. Its modern development is motivated by two seemingly unrelated
directions. One is the introduction of k-Schur functions in the study of
Macdonald polynomial positivity, a mostly combinatorial branch of
symmetric function theory. The other direction is the study of the
Schubert bases of the (co)homology of the affine Grassmannian, an
algebro-topological formulation of a problem in enumerative geometry.
This is the first introductory text on this subject. It contains many
examples in Sage, a free open source general purpose mathematical
software system, to entice the reader to investigate the open problems.
This book is written for advanced undergraduate and graduate students,
as well as researchers, who want to become familiar with this
fascinating new field.