Reducible characteristic cycles of Harish-Chandra modules for and the Kashiwara-Saito singularity

Abstrakt

We give examples of reducible characteristic cycles for irreducible Harish-Chandra modules for U(p, q) by analyzing a four-dimensional singular subvariety of We relate this singularity to the Kashiwara-Saito singularity arising for Schubert varieties for with reducible characteristic cycles, as well as recent related examples of Williamson. In particular, this gives another explanation of the simple highest weight modules for with reducible associated varieties that Williamson discovered.

Klíčová slova

• Characteristic cycles
• characteristic varieties
• Harish-Chandra modules
• Schubert varieties