160,915 research outputs found
The mod 2 cohomology of the infinite families of Coxeter groups of type B and D as almost Hopf rings
We describe a Hopf ring structure on the direct sum of the cohomology groups
of the Coxeter
groups of type , and an almost-Hopf ring structure on the direct sum of
the cohomology groups of the Coxeter groups of type , with coefficient in the field
with two elements . We give presentations with generators and
relations, determine additive bases and compute the Steenrod algebra action.
The generators are described both in terms of a geometric construction by De
Concini and Salvetti and in terms of their restriction to elementary abelian
2-subgroups.Comment: 32 page
Stable characteristic classes of smooth manifold bundles
Characteristic classes of oriented vector bundles can be identified with
cohomology classes of the disjoint union of classifying spaces BSO_n of special
orthogonal groups SO_n with n=0,1,... A characteristic class is stable if it
extends to a cohomology class of a homotopy colimit BSO of classifying spaces
BSO_n.
Similarly, characteristic classes of smooth oriented manifold bundles with
fibers given by oriented closed smooth manifolds of a fixed dimension d\ge 0
can be identified with cohomology classes of the disjoint union of classifying
spaces BDiff M of orientation preserving diffeomorphism groups of oriented
closed manifolds of dimension d. A characteristic class is stable if it extends
to a cohomology class of a homotopy colimit of spaces BDiff M. We show that
each rational stable characteristic class of oriented manifold bundles of even
dimension d is tautological, e.g., if d=2, then each rational stable
characteristic class is a polynomial in terms of Miller-Morita-Mumford classes.Comment: 52 page
A summary of research in elementary school social studies (1948-1950)
Thesis (Ed.M.)--Boston Universit
Orbifold Quantum Cohomology
This is a research announcement of the theory of orbifold quantum cohomology.Comment: Revised version, adding more reference
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