866 research outputs found
Box splines and the equivariant index theorem
In this article, we start to recall the inversion formula for the convolution
with the Box spline. The equivariant cohomology and the equivariant K-theory
with respect to a compact torus G of various spaces associated to a linear
action of G in a vector space M can be both described using some vector spaces
of distributions, on the dual of the group G or on the dual of its Lie algebra.
The morphism from K-theory to cohomology is analyzed and the multiplication by
the Todd class is shown to correspond to the operator (deconvolution) inverting
the semidiscrete convolution with a box spline. Finally, the multiplicities of
the index of a G-transversally elliptic operator on M are determined using the
infinitesimal index of the symbol.Comment: 44 page
Infinitesimal index: cohomology computations
In this note several computations of equivariant cohomology groups are
performed. For the compactly supported equivariant cohomology, the notion of
infinitesimal index developed in arXiv:1003.3525, allows to describe these
groups in terms of certain spaces of distributions arising in the theory of
splines.
The new version contains a large number of improvements
Counting Integer flows in Networks
This paper discusses new analytic algorithms and software for the enumeration
of all integer flows inside a network. Concrete applications abound in graph
theory \cite{Jaeger}, representation theory \cite{kirillov}, and statistics
\cite{persi}. Our methods clearly surpass traditional exhaustive enumeration
and other algorithms and can even yield formulas when the input data contains
some parameters. These methods are based on the study of rational functions
with poles on arrangements of hyperplanes
How to Integrate a Polynomial over a Simplex
This paper settles the computational complexity of the problem of integrating
a polynomial function f over a rational simplex. We prove that the problem is
NP-hard for arbitrary polynomials via a generalization of a theorem of Motzkin
and Straus. On the other hand, if the polynomial depends only on a fixed number
of variables, while its degree and the dimension of the simplex are allowed to
vary, we prove that integration can be done in polynomial time. As a
consequence, for polynomials of fixed total degree, there is a polynomial time
algorithm as well. We conclude the article with extensions to other polytopes,
discussion of other available methods and experimental results.Comment: Tables added with new experimental results. References adde
Computation of the highest coefficients of weighted Ehrhart quasi-polynomials of rational polyhedra
This article concerns the computational problem of counting the lattice
points inside convex polytopes, when each point must be counted with a weight
associated to it. We describe an efficient algorithm for computing the highest
degree coefficients of the weighted Ehrhart quasi-polynomial for a rational
simple polytope in varying dimension, when the weights of the lattice points
are given by a polynomial function h. Our technique is based on a refinement of
an algorithm of A. Barvinok [Computing the Ehrhart quasi-polynomial of a
rational simplex, Math. Comp. 75 (2006), pp. 1449--1466] in the unweighted case
(i.e., h = 1). In contrast to Barvinok's method, our method is local, obtains
an approximation on the level of generating functions, handles the general
weighted case, and provides the coefficients in closed form as step polynomials
of the dilation. To demonstrate the practicality of our approach we report on
computational experiments which show even our simple implementation can compete
with state of the art software.Comment: 34 pages, 2 figure
Osteopathy Complete
The human system is, to all intents and purposes, a wonderful machine, capable of running for an indefinite period of time, unless interfered with by accidents, dislocations, contraction of muscles, obstruction of the nerve-force, or the circulation of the nutritive fluids of the body. The author consulted such works as Gx\u27ay, Landois, Saunders, and Musser, with an earnest desire to advance the cause of Osteopathy, and endeavored to be accurate, concise, and modern.https://digitalcommons.pcom.edu/classic_med_works/1009/thumbnail.jp
Computing the -coverage of a wireless network
Coverage is one of the main quality of service of a wirelessnetwork.
-coverage, that is to be covered simultaneously by network nodes, is
synonym of reliability and numerous applicationssuch as multiple site MIMO
features, or handovers. We introduce here anew algorithm for computing the
-coverage of a wirelessnetwork. Our method is based on the observation that
-coverage canbe interpreted as layers of -coverage, or simply
coverage. Weuse simplicial homology to compute the network's topology and
areduction algorithm to indentify the layers of -coverage. Weprovide figures
and simulation results to illustrate our algorithm.Comment: Valuetools 2019, Mar 2019, Palma de Mallorca, Spain. 2019. arXiv
admin note: text overlap with arXiv:1802.0844
Coefficients of Sylvester's Denumerant
For a given sequence of positive integers, we consider
the combinatorial function that counts the nonnegative
integer solutions of the equation , where the right-hand side is a varying
nonnegative integer. It is well-known that is a
quasi-polynomial function in the variable of degree . In combinatorial
number theory this function is known as Sylvester's denumerant.
Our main result is a new algorithm that, for every fixed number , computes
in polynomial time the highest coefficients of the quasi-polynomial
as step polynomials of (a simpler and more explicit
representation). Our algorithm is a consequence of a nice poset structure on
the poles of the associated rational generating function for
and the geometric reinterpretation of some rational
generating functions in terms of lattice points in polyhedral cones. Our
algorithm also uses Barvinok's fundamental fast decomposition of a polyhedral
cone into unimodular cones. This paper also presents a simple algorithm to
predict the first non-constant coefficient and concludes with a report of
several computational experiments using an implementation of our algorithm in
LattE integrale. We compare it with various Maple programs for partial or full
computation of the denumerant.Comment: minor revision, 28 page
Osteopathy: The New Science of Healing
This author knew that Osteopathy was destined to revolutionize the medical world and aims to reach the masses. While Barber gives Dr. Still credit for the new science which he discovered, he differs with him as to the true cause of the results reached by the Osteopath. Barber states that the true cause of all disease may be traced to some muscle which has contracted and for some unaccountable reason has failed to relax, thus interfering with all the forces of life.https://digitalcommons.pcom.edu/classic_med_works/1011/thumbnail.jp
- …