Quotients of unstable subvarieties and moduli spaces of sheaves of fixed Harder–Narasimhan type
نویسندگان
چکیده
When a reductive group G acts linearly on a complex projective scheme X, there is a stratification of X into G-invariant locally closed subschemes, with an open stratum X formed by the semistable points in the sense of Mumford’s geometric invariant theory which has a categorical quotient X → X//G. In this article, we describe a method for constructing quotients of the unstable strata. As an application, we construct moduli spaces of sheaves of fixed Harder– Narasimhan type with some extra data (an ‘n-rigidification’) on a projective base.
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