Strict Bott-Samelson Resolutions of Schubert Varieties

Abstract

We explore the relationship between two desingularization techniques for Schubert varieties. The Bott-Samelson resolution is the more common of the two, but it fails to encompass many properties that Hironaka resolutions provide, in particular, being an isomorphism over the smooth locus. Using a computer search, a list of cases where Bott-Samelson resolutions having this "strictness" property is compiled for the $n=5,6$ cases. A conjecture based on these results is formulated and is subsequently verified for $n=7,8$. A comparison between Bott-Samelson resolutions and blow-ups is also provided.

arXiv comment18 pages; Sage code included in ancillary file; Accepted for publication in Experimental Mathematics; Revised version includes new content relating this work to known research. It also includes updated computer results