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Intersection theory of moduli space of stable $$n$$-pointed curves of genus zero. (English) Zbl 0768.14002
From the introduction: “This paper concerns the intersection theory of the moduli space of $$n$$-pointed stable curves of genus 0. F. F. Knudsen [Math. Scand. 52, 161-199 (1983; Zbl 0506.14019)] constructs the space, which we call $$X_ n$$, and shows it is a smooth complete variety. We give an alternative construction of $$X_ n$$, via a sequence of blow- ups of smooth varieties along smooth codimension two subvarieties, and using our construction:
(1) We show that the canonical map from the Chow groups to homology (in characteristic zero) $$A_ *(X_ n)@>cl>>H_ *(X_ n)$$ is an isomorphism.
(2) We give a recursive formula for the Betti numbers of $$X_ n$$.
(3) We give an inductive recipe for determining dual bases in the Chow ring $$A^*(X_ n)$$.
(4) We calculate the Chow ring. It is generated by divisors, and we express it as a quotient of a polynomial ring by giving generators for the ideal of relations.
Once we have described $$X_ n$$ via blow-ups, our results follow from application of some general results on the Chow rings of regular blow-ups which we develop in an appendix”.

##### MSC:
 14C17 Intersection theory, characteristic classes, intersection multiplicities in algebraic geometry 14H10 Families, moduli of curves (algebraic) 14C05 Parametrization (Chow and Hilbert schemes)
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