A simplicial groupoid for plethysm

The Monodromy Groupoid of a Lie Groupoid

R esum e: Nous d emontrons que, sous des circomstances g en erales, l'union disjoint des couvertes universales des etoiles d'un groupo de de Lie admet le structure d'un groupo de de Lie auquel que le projection a une propri et e de monodromie sur les extensions des morphismes emousse. Ca compl etes une conte d etailles des r esultats annonc es par J. Pradines. Introduction The notion of monodro...

A Note on Plethysm

For a positive integer k let k denote {1, ... , k}, and let §k denote the symmetric group on k. For positive integers m and n let Im.n be the set of all dissections of mn into sets of cardinality m. §mn acts primitively on Im.n in a natural way, and the stabilizer of a point in this representation is the wreath product §m w§n. Denote llm.n I by r:xm.n; r:xm.n is equal to the index of §m w§n in ...

Gaussian Maps and Plethysm

New methods for constructing shellable simplicial complexes

A clutter $mathcal{C}$ with vertex set $[n]$ is an antichain of subsets of $[n]$, called circuits, covering all vertices. The clutter is $d$-uniform if all of its circuits have the same cardinality $d$. If $mathbb{K}$ is a field, then there is a one-to-one correspondence between clutters on $V$ and square-free monomial ideals in $mathbb{K}[x_1,ldots,x_n]$ as follows: To each clutter $mathcal{C}...

GROUPOID ASSOCIATED TO A SMOOTH MANIFOLD

‎In this paper‎, ‎we introduce the structure of a groupoid associated to a vector field‎ ‎on a smooth manifold‎. ‎We show that in the case of the $1$-dimensional manifolds‎, ‎our‎ ‎groupoid has a‎ ‎smooth structure such that makes it into a Lie groupoid‎. ‎Using this approach‎, ‎we associated to‎ ‎every vector field an equivalence‎ ‎relation on the Lie algebra of all vector fields on the smooth...