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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)
Full Text: DOI

References:

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