arXiv 0909.37652009-09math.RT

Primitive spherical systems

P. Bravi

备注：: v1: 34 pages. v2: 70 pages

英文摘要：

A spherical system is a combinatorial object, arising in the theory of wonderful varieties, defined in terms of a root system. All spherical systems can be obtained by means of some general combinatorial procedures (such as parabolic induction and wonderful fiber product) from the so-called primitive spherical systems. Here we classify primitive spherical systems. As an application, we prove that the quotients of a spherical system are in correspondence with the so-called distinguished subsets of colors.

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