Degeneration of point configurations in the projective plane. (English) Zbl 0731.14036
Summary: In this paper we construct a compactification of the moduli space \(B^*_ n=({\mathbb{P}}^ n_ 2\setminus \Delta)/PGL(3)\) of n-point configurations in the plane in general position modulo linear transformations. This compactification \(B_ n\) is an analogue to the space of n-pointed trees of projective lines and a generalization of a compactification of orbit spaces of more general group actions. We relate the fibres of the universal n-point configuration \(F_ n\to B_ n\) to schemes associated with the Bruhat-Tits building and give explicit descriptions in the cases \(n=5\) and \(n=6\).
MSC:
14N05 | Projective techniques in algebraic geometry |
14G20 | Local ground fields in algebraic geometry |
14M17 | Homogeneous spaces and generalizations |
14D20 | Algebraic moduli problems, moduli of vector bundles |
05B30 | Other designs, configurations |
14L30 | Group actions on varieties or schemes (quotients) |
Keywords:
compactification of the moduli space; compactification of orbit spaces; group actions; Bruhat-Tits buildingReferences:
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