We compute the L-characteristic cycle of an A-hypergeometric system and higher Euler–Koszul homology modules of the toric ring. We also prove upper semicontinuity results about the multiplicities in these cycles and apply our results to analyze the behavior of Gevrey solution spaces of the system.
Bibliographical noteFunding Information:
CB was partially supported by NSF Grants DMS 1661962, DMS 1440537, OISE 0964985. MCFF was partially supported by MTM2016-75024-P, PP2014-2397, P12-FQM-2696 and FEDER. MSC2010: primary 13N10; secondary 14M25, 32C38, 33C70. Keywords: A-hypergeometric system, toric ring, D-module, characteristic cycle, irregularity sheaf, Gevrey series.
CB was partially supported by NSF Grants DMS 1661962, DMS 1440537, OISE 0964985. MCFF was partially supported by MTM2016-75024-P, PP2014-2397, P12-FQM-2696 and FEDER.We are grateful to Francisco Jes?s Castro Jim?nez, Laura Felicia Matusevich, and Uli Walther for helpful conversations related to this work. Fern?ndez-Fern?ndez would like to thank the School of Mathematics of the University of Minnesota for the hospitality during her visit to work on this paper with Berkesch.
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- A-hypergeometric system
- Characteristic cycle
- Gevrey series
- Irregularity sheaf
- Toric ring