1st Edition

Handbook of Combinatorial Algebraic Geometry Subvarieties of the Flag Variety

Edited By Erik Insko, Martha Precup, Edward Richmond Copyright 2026
1060 Pages 224 Color Illustrations
by Chapman & Hall

1060 Pages 224 Color Illustrations
by Chapman & Hall

This handbook presents a thorough introduction to current topics of mathematical research in combinatorial algebraic geometry. The editors’ aim is to introduce researchers to key literature from the past 20-30 years needed to address open questions in the field. The chapters of Handbook of Combinatorial Algebraic Geometry: Subvarieties of the Flag Variety give concrete, computational examples... Read more

Part 1: Flag varieties and Schubert varieties

1. Introduction to the Cohomology of the Flag Variety

Sara C. Billey, Yibo Gao, and Brendan Pawlowski

Part 2: Subvarieties of the flag variety             

2. Schubert Geometry and Combinatorics       

Alexander Woo and Alexander Yong

3. Richardson varieties, projected Richardson varieties and positroid varieties            

David E Speyer

4. Torus orbit closures in the flag variety            

Eunjeong Lee, Mikiya Masuda, and Seonjeong Park

5. Pattern avoidance and K-orbit closures        

William M. McGovern

Part 3: Hessenberg Varieties 

6. An Introduction to Hessenberg Varieties      

Julianna Tymoczko

7. The cohomology rings of regular nilpotent Hessenberg varieties     

Megumi Harada and Tatsuya Horiguchi

8. Hessenberg varieties and algebraic combinatorics of hyperplane arrangements

Satoshi Murai

9.  Combinatorics and Hessenberg Varieties  

John Shareshian and Michelle L. Wachs

Part 4: Additional topics          

10. Generalizations of the flag variety tied to the Macdonald-theoretic delta operators

Brendon Rhoades

11. Nil-Hecke rings and Schubert calculus

Edward Richmond and Kirill Zainoulline

12. Coxeter groups and Billey–Postnikov decompositions

Suho Oh and Edward Richmond

Biography

Erik Insko received his Ph.D. in Mathematics in 2012 under the guidance of Julianna Tymoczko. He served on the faculty at Florida Gulf Coast University from 2012 to 2023 before joining Central College as a Professor of Mathematics and Computer Science. He enjoys mentoring student researchers and was awarded the Mid-Career Faculty Mentor Award by the Council on Undergraduate Research in the Mathematics and Computer Science Division in 2021.  His research interests lie in Algebraic Combinatorics and Graph Theory. He has 26 publications indexed on MathSciNet.

Martha Precup received her Ph.D. in Mathematics from the University of Notre Dame in 2013 under the supervision of Samuel Evens. She subsequently held postdoctoral fellowships at Baylor University and Northwestern University. Since 2018, she has been a faculty member at Washington University in St. Louis, where she is now an Associate Professor. Precup has an active and growing research program, with 19 publications listed on MathSciNet. She previously held a single–PI NSF research grant and currently holds an NSF CAREER award. She was recently awarded the 2026–2027 Ruth I. Michler Prize by the Association for Women in Mathematics.

Edward Richmond received his Ph.D. in Mathematics in 2008 from the University of North Carolina at Chapel Hill under the direction of Prakash Belkale. He has held postdoctoral appointments at the University of Oregon and the University of British Columbia. Since 2014, he has been a faculty member at Oklahoma State University, where he is now a Professor and the Director of Graduate Studies. His research lies in algebraic combinatorics and Lie theory, with a focus on Schubert varieties, flag varieties, and related combinatorial and geometric objects. He has 23 publications listed on MathSciNet and his work has been supported by the NSA and the Simons Foundation.