Secondary Characteristic Classes of Surface Bundles
نویسنده
چکیده
The Miller-Morita-Mumford classes associate to an oriented surface bundle E → B a class κi(E) ∈ H 2i(B;Z). In this note we define for each prime p and each integer i ≥ 1 a secondary characteristic class λi(E) ∈ H2i(p−1)−2(B;Z)/Zκi(p−1)−1. The mod p reduction λi(E) ∈ H∗(B;Fp) has zero indeterminacy and satisfies pλi(E) = κi(p−1)−1(E) ∈ H ∗(B;Z/p2).
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