The moduli space of n points on the line is cut out by simple quadrics when n is not six

dc.creatorHoward, Benjamin
dc.creatorMillson, John
dc.creatorSnowden, Andrew
dc.creatorVakil, Ravi
dc.date2006-07-16
dc.date.accessioned2026-07-07T07:18:25Z
dc.date.available2026-07-07T07:18:25Z
dc.descriptionA central question in invariant theory is that of determining the relations among invariants. Geometric invariant theory quotients come with a natural ample line bundle, and hence often a natural projective embedding. This question translates to determining the equations of the moduli space under this embedding. This note deals with one of the most classical quotients, the space of ordered points on the projective line. We show that under any linearization, this quotient is cut out (scheme-theoretically) by a particularly simple set of quadric relations, with the single exception of the Segre cubic threefold (the space of six points with equal weight). Unlike many facts in geometric invariant theory, these results (at least for the stable locus) are field-independent, and indeed work over the integers.
dc.description25 pages, 16 figures
dc.identifierhttps://arxiv.org/abs/math/0607372
dc.identifierhttp://arxiv.org/abs/math/0607372
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/114294
dc.subjectAlgebraic Geometry
dc.subjectPrimary 14L24; Secondary 14D22, 14H10
dc.titleThe moduli space of n points on the line is cut out by simple quadrics when n is not six
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