Self-intersections of Immersions and Steenrod Operations
نویسنده
چکیده
We present a formula describing the action of a generalised Steenrod operation of Z2-type [14] on the cohomology class represented by a proper self-transverse immersion f : M X. Our formula depends only on the Umkehr map, the characteristic classes of the normal bundle, and the class represented by the double point immersion of f . This generalises a classical result of R. Thom [13]: If α ∈ H(X;Z2) is the ordinary cohomology class represented by f : M X, then Sq(α) = f∗wi(νf ).
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تاریخ انتشار 2005