We study the orbits of G = GL(V ) in the enhanced nilpotent cone V Ã—N , where N is the variety of nilpotent endomorphisms of V . These orbits are parametrized by bipartitions of n = dim V , and weâ€¦ (More)

We prove analogues for sub-posets of the Dowling lattices of the results of Calderbank, Hanlon, and Robinson on homology of sub-posets of the partition lattices. The technical tool used is the wreathâ€¦ (More)

We study the rational cohomology groups of the real De Conciniâ€“Procesi model corresponding to a finite Coxeter group, generalizing the type-A case of the moduli space of stable genus 0 curves withâ€¦ (More)

We generalize Joyalâ€™s theory of species to the case of functors from the groupoid of finite sets to the category of varieties over Fq . These have cycle index series defined by counting fixed pointsâ€¦ (More)

Let Hâˆ—(Be) be the cohomology of the Springer fibre for the nilpotent element e in a simple Lie algebra g, on which the Weyl group W acts by the Springer representation. Let Î›V denote the ith exteriorâ€¦ (More)

The anatomy of the male and female reproductive systems was investigated in the long-tailed butterfly ray Gymnura poecilura using gross observation and light microscopy. The testes are highlyâ€¦ (More)

The wreath product W (r, n) of the cyclic group of order r and the symmetric group Sn acts on the corresponding projective hyperplane complement, and on its wonderful compactification as defined byâ€¦ (More)

We show that two Weyl group actions on the Springer sheaf with arbitrary coefficients, one defined by Fourier transform and one by restriction, agree up to a twist by the sign character. Thisâ€¦ (More)

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching andâ€¦ (More)

We continue the study of the closures of GL(V )-orbits in the enhanced nilpotent cone V Ã— N begun by the first two authors. We prove that each closure is an invariant-theoretic quotient of aâ€¦ (More)