Abelian group actions on algebraic varieties with one fixed point
(joint work with Amir Assadi and Rebecca Barlow)

Theorem: Let X be a complete algebraic variety over an algebraically closed field of characteristic p>=0, and let G be a finite abelian group acting on X. Assume the order of G is l^r, where l is a prime different from p. If the fixed point set consists of exactly one point x, then X is singular in X.

Corollary: If X is smooth then G has either no fixed point or at least two of them.

This is an algebraic analogue of (much deeper) results of Conner-Floyd, Atiyah-Bott and others in the topological category.

Appeared in: Mathematische Zeitschrift 210 (1992) 129-136

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Last updated: December 20, 2003