Graphs of schemes associated to group actions

2023-12-01
Let X be a proper algebraic scheme over an algebraically closed field. We assume that atorus T acts on X such that the action has isolated fixed points. The T-graph of X canbe defined using the fixed points and the one-dimensional orbits of the T-action. If theupper Borel subgroup of the general linear group with maximal torus T acts on X, thenwe can define a second graph associated to X, called the A-graph of X. We prove thatthe A-graph of X is connected if and only if X is connected. We use this result to giveproof of Hartshorne’s theorem on the connectedness of the Hilbert scheme in the case ofd points in n-dimensional projective space.
HACETTEPE JOURNAL OF MATHEMATICS AND STATISTICS
Citation Formats
A. U. Ö. Kişisel and E. Özkan, “Graphs of schemes associated to group actions,” HACETTEPE JOURNAL OF MATHEMATICS AND STATISTICS, pp. 1–10, 2023, Accessed: 00, 2023. [Online]. Available: https://dergipark.org.tr/en/download/article-file/2779510.