Let H be the Hecke algebra of a Coxeter group (W, S). In studying the Kazhdan-Lusztig basis of H, Deodhar considered products , where  is a sequence of generators in S. He defined and counted certain "defects" of such sequences to express the corresponding products in the natural basis of H. We extend his definition to sequences of more general elements of W and thus express more general products in the natural basis of H, in the case that W has type A or BC.

This is joint work with Gavin Hobbs, Tommy Parisi, and Jiayuan Wang.