Friday, 14 October 2011

Fixed Point Property in Algebraic Geometry

I am wondering about the following problem: for which (say smooth, complex, connected) algebraic varieties X does the statement any regular map XtoX has a fixed point hold?
MathSciNet search does not reveal anything in this topic.



This is true for mathbbPn (because its cohomology is mathbbZ in even dimensions
and 0 otherwise, and the pullback of an effective cycle is effective, so all summands
in the Lefschetz fixed point formula are nonnegative, and the 0-th is positive
-- is this a correct argument?). Is it true for varieties with cohomology generated by algebraic cycles (i.e. hp,q(X)=0 unless p=q and satisfying Hodge conjecture), for example for Grassmannians, toric varieties, etc.? This is not at all clear that the traces of f on cohomology will be nonnegative.



Probably you have lots of counterexamples. What about positive results?

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