Honeycombs, hives, and puzzles; or, Hermitian sums, $GL_n({\Bbb C})$ tensor products, and Schubert calculus on Grassmannians
Allen Knutson, Terence Tao
American Mathematical Society
In preparation

This is a self-contained introduction to the combinatorial tools of honeycombs, hives, and puzzles, and their applications to linear algebra, representation theory, and algebraic geometry. This book will not be finished until 2008 at the earliest.