On the Yagita Invariant of Mapping Class Groups
نویسندگان
چکیده
Let Γ denote a group of finite virtual cohomological dimension and p a prime. If the cohomology ring H∗(Γ;Fp) has Krull dimension one, the p-period of Γ is defined; it measures the periodicity of H∗(Γ;Fp) in degrees above the virtual cohomological dimension of Γ. The Yagita invariant p(Γ) of Γ is a natural generalization of the p-period to groups with H∗(Γ;Fp) of Krull dimension larger than one. We compute the Yagita invariant p(Γg) for the mapping class group Γg with respect to an arbitrary odd regular prime p.
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