Publications associées à The mixing time of the Dikin walk in a polytope-A simple proof

MIXING FOR GENERIC ROUGH SHEAR FLOWS

We study mixing and diffusion properties of passive scalars driven by generic rough shear flows. Genericity is here understood in the sense of prevalence, and (ir)regularity is measured in the Besov-Nikolskii scale B\alpha 1,\infty, \alpha \in (0,1). We pr ...

Siam Publications2023

New Results in Integer and Lattice Programming

Christoph Hunkenschröder

An integer program (IP) is a problem of the form

\min \{f(x) : \, Ax = b, \ l \leq x \leq u, \ x \in \Z^n\}

, where

A \in \Z^{m \times n}

,

b \in \Z^m

,

l,u \in \Z^n

, and

f: \Z^n \rightarrow \Z

is a separable convex objective function. The problem o ...

EPFL2020

Tropical Ehrhart Theory and Tropical Volume

Georg Peter Loho, Matthias Schymura

We introduce a novel intrinsic volume concept in tropical geometry. This is achieved by developing the foundations of a tropical analog of lattice point counting in polytopes. We exhibit the basic properties and compare it to existing measures. Our exposit ...

2019

Extended Formulations from Communication Protocols in Output-Efficient Time

Yuri Faenza, Manuel Francesco Aprile

Deterministic protocols are well-known tools to obtain extended formulations, with many applications to polytopes arising in combinatorial optimization. Although constructive, those tools are not output-efficient, since the time needed to produce the exten ...

SPRINGER INTERNATIONAL PUBLISHING AG2019

On 2-Level Polytopes Arising In Combinatorial Settings

Alfonso Bolívar Cevallos Manzano, Yuri Faenza, Manuel Francesco Aprile

2-level polytopes naturally appear in several areas of pure and applied mathematics, including combinatorial optimization, polyhedral combinatorics, communication complexity, and statistics. In this paper, we present a study of some 2-level polytopes arisi ...

SIAM Publications2018

On some problems related to 2-level polytopes

Manuel Francesco Aprile

In this thesis we investigate a number of problems related to 2-level polytopes, in particular from the point of view of the combinatorial structure and the extension complexity. 2-level polytopes were introduced as a generalization of stable set polytopes ...

EPFL2018

Non-Normal Very Ample Polytopes - Constructions and Examples

Michal Lason

We answer several questions posed by Beck, Cox, Delgado, Gubeladze, Haase, Hibi, Higashitani, and Maclagan in [Cox et al. 14, Question 3.5 (1),(2), Question 3.6], [Beck et al. 15, Conjecture 3.5(a),(b)], and [Hasse et al. 07, Open question 3 (a),(b) p. 231 ...

Taylor & Francis Inc2017

Extension complexity of stable set polytopes of bipartite graphs

Yuri Faenza, Manuel Francesco Aprile

The extension complexity xc(P) of a polytope P is the minimum number of facets of a polytope that affinely projects to P. Let G be a bipartite graph with n vertices, m edges, and no isolated vertices. Let STAB(G) be the convex hull of the stable sets of G. ...

Springer2017

On vertices and facets of combinatorial 2-level polytopes

Alfonso Bolívar Cevallos Manzano, Yuri Faenza, Manuel Francesco Aprile

2-level polytopes naturally appear in several areas of mathematics, including combinatorial optimization, polyhedral combinatorics, communication complexity, and statistics. We investigate upper bounds on the product of the number of facets and the number ...

Springer2016

Comments on: Recent progress on the combinatorial diameter of polytopes and simplicial complexes

Friedrich Eisenbrand

This paper features two main contributions. On the one hand, it gives an impressive survey on the progress on the diameter problem, including the breakthrough of the author with his disproof of the Hirsch conjecture among many other recent results. On the ...

Springer2013

Heat Management for Process Intensification of Fast Exothermic Reactions in Microstructured Reactors

Julien Haber

Nowadays, the production in fine chemical and pharmaceutical industry is mostly carried out in large scale batch reactors having typically dimensions of a few meters to satisfy the demand of the market. Even though this technology has been widely used and ...

EPFL2013

Weakly regular subdivisions

Lionel Pournin

It is shown that 2-dimensional subdivisions can be made regular by moving their vertices within parallel 1-dimensional spaces. As a consequence, any 2-dimensional subdivision is projected from the boundary complex of a 4-polytope. ...

Springer-Verlag2012

Belt distance between facets of space-filling zonotopes

To every d-dimensional polytope P with centrally symmetric facets one can assign a “subway map” such that every line of this “subway” contains exactly the facets parallel to one of the ridges of P. The belt diameter of P is the maximum number of subway lin ...

2012

Computational Methods For Structured Sparse Component Analysis of Convolutive Speech Mixtures

Hervé Bourlard, Afsaneh Asaei, Volkan Cevher

We cast the under-determined convolutive speech separation as sparse approximation of the spatial spectra of the mixing sources. In this framework we compare and contrast the major practical algorithms for structured sparse recovery of speech signal. Speci ...

2012

Effect of mixing on the early hydration of alite and OPC systems

Patrick Juilland, Karen Scrivener, Emmanuel Gallucci, Aditya Kumar

The kinetics of hydration of cementitious materials is sensitive to the mixing procedure. High shear mixing conditions lead to an increase in the kinetics of hydration at early age compared to low shearing conditions such as hand mixing. In this study the ...

Pergamon-Elsevier Science Ltd2012

Mixing efficiency and energy consumption for five generic microchannel designs

Lioubov Kiwi, Albert Renken, Madhvanand Namadeo Kashid

Mixing is an essential part of chemical processes. In the present work, homogeneous mixing at relatively high throughput for a single microchannel (of 1-18 mL/min) was investigated in microchannels with different dimensions, cross sections and mixing eleme ...

2011

A linear equation for Minkowski sums of polytopes relatively in general position

Christophe Weibel

The objective of this paper is to study a special family of Minkowski sums, that is of polytopes relatively in general position. We show that the maximum number of faces in the sum can be attained by this family. We present a new linear equation that is sa ...

2010

Indecomposable Coverings with Concave Polygons

Doemoetoer Palvoelgyi

We show that for any concave polygon that has no parallel sides and for any k, there is a k-fold covering of some point set by the translates of this polygon that cannot be decomposed into two coverings. Moreover, we give a complete classification of open ...

Springer-Verlag2010

Determination of a scale-up factor from mixing time studies in orbitally shaken bioreactors

Christos Comninellis, Florian Maria Wurm, Mohamed Farhat, David Hacker, Stéphanie Tissot

Efficient mixing in bioreactors is essential in order to avoid concentration gradients which can be harmful for mammalian cells. To study mixing and its scalability in orbitally shaken cylindrical bioreactors, we measured mixing times in containers with no ...

Elsevier2010

Minkowski sums of polytopes : combinatorics and computation

Christophe Weibel

Minkowski sums are a very simple geometrical operation, with applications in many different fields. In particular, Minkowski sums of polytopes have shown to be of interest to both industry and the academic world. This thesis presents a study of these sums, ...

EPFL2007