Abstract
The subgroup \(K=\mathrm{GL}_p \times \mathrm{GL}_q\) of \(\mathrm{GL}_{p+q}\) acts on the (complex) flag variety \(\mathrm{GL}_{p+q}/B\) with finitely many orbits. We introduce a family of polynomials specializing representatives for cohomology classes of the orbit closures in the Borel model. We define and study \(K\)-orbit determinantal ideals to support the geometric naturality of these representatives. Using a modification of these ideals, we describe an analogy between two local singularity measures: the \(H\)-polynomials and the Kazhdan–Lusztig–Vogan polynomials.
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Acknowledgments
We wish to thank Bill Graham, Allen Knutson, William McGovern, Oliver Pechenik, Hal Schenck, Peter Trapa, Hugh Thomas, and Alexander Woo for helpful correspondence. We also thank the anonymous referee for his/her useful suggestions. A.Y. was supported by NSF Grants. This text was completed while A.Y. was a Helen Corley Petit scholar at UIUC.
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Appendix
Appendix
Below we give the polynomials \(\Upsilon _{\gamma }(X;Y)\) for all \(\gamma \in \mathtt{Clans}_{2,2}\).
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Wyser, B.J., Yong, A. Polynomials for \(\mathrm{GL}_p\times \mathrm{GL}_q\) orbit closures in the flag variety. Sel. Math. New Ser. 20, 1083–1110 (2014). https://doi.org/10.1007/s00029-014-0152-z
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DOI: https://doi.org/10.1007/s00029-014-0152-z