1,106 research outputs found
On certain families of sparse numerical semigroups with Frobenius number even
This paper is about sparse numerical semigroups and applications in the Weierstrass semigroups theory. We describe and find the genus of certain families of sparse numerical semigroups with Frobenius number even and we also study the realization of the elements on these families as Weierstrass semigroups
Estimating long term behavior of flows without trajectory integration: the infinitesimal generator approach
The long-term distributions of trajectories of a flow are described by
invariant densities, i.e. fixed points of an associated transfer operator. In
addition, global slowly mixing structures, such as almost-invariant sets, which
partition phase space into regions that are almost dynamically disconnected,
can also be identified by certain eigenfunctions of this operator. Indeed,
these structures are often hard to obtain by brute-force trajectory-based
analyses. In a wide variety of applications, transfer operators have proven to
be very efficient tools for an analysis of the global behavior of a dynamical
system.
The computationally most expensive step in the construction of an approximate
transfer operator is the numerical integration of many short term trajectories.
In this paper, we propose to directly work with the infinitesimal generator
instead of the operator, completely avoiding trajectory integration. We propose
two different discretization schemes; a cell based discretization and a
spectral collocation approach. Convergence can be shown in certain
circumstances. We demonstrate numerically that our approach is much more
efficient than the operator approach, sometimes by several orders of magnitude
Cyclotomic coefficients: gaps and jumps
We improve several recent results by Hong, Lee, Lee and Park (2012) on gaps
and Bzd\c{e}ga (2014) on jumps amongst the coefficients of cyclotomic
polynomials. Besides direct improvements, we also introduce several new
techniques that have never been used in this area.Comment: 25 page
Cyclotomic numerical semigroups
Given a numerical semigroup , we let be its semigroup polynomial. We study cyclotomic numerical semigroups;
these are numerical semigroups such that has all its roots
in the unit disc. We conjecture that is a cyclotomic numerical semigroup if
and only if is a complete intersection numerical semigroup and present some
evidence for it. Aside from the notion of cyclotomic numerical semigroup we
introduce the notion of cyclotomic exponents and polynomially related numerical
semigroups. We derive some properties and give some applications of these new
concepts.Comment: 17 pages, accepted for publication in SIAM J. Discrete Mat
Operator splitting for dissipative delay equations
We investigate Lie-Trotter product formulae for abstract nonlinear evolution
equations with delay. Using results from the theory of nonlinear contraction
semigroups in Hilbert spaces, we explain the convergence of the splitting
procedure. The order of convergence is also investigated in detail, and some
numerical illustrations are presented.Comment: to appear in Semigroup Foru
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