2,790 research outputs found
Acyclic orientations with path constraints
Many well-known combinatorial optimization problems can be stated over the
set of acyclic orientations of an undirected graph. For example, acyclic
orientations with certain diameter constraints are closely related to the
optimal solutions of the vertex coloring and frequency assignment problems. In
this paper we introduce a linear programming formulation of acyclic
orientations with path constraints, and discuss its use in the solution of the
vertex coloring problem and some versions of the frequency assignment problem.
A study of the polytope associated with the formulation is presented, including
proofs of which constraints of the formulation are facet-defining and the
introduction of new classes of valid inequalities
Integer programming approaches for minimum stabbing problems
The problem of finding structures with minimum stabbing number has received considerable attention from researchers. Particularly, [10] study the minimum stabbing number of perfect matchings (mspm), spanning trees (msst) and triangulations (mstr) associated to set of points in the plane. The complexity of the mstr remains open whilst the other two are known to be . This paper presents integer programming (ip) formulations for these three problems, that allowed us to solve them to optimality through ip branch-and-bound (b&b) or branch-and-cut (b&c) algorithms. Moreover, these models are the basis for the development of Lagrangian heuristics. Computational tests were conducted with instances taken from the literature where the performance of the Lagrangian heuristics were compared with that of the exact b&b and b&c algorithms. The results reveal that the Lagrangian heuristics yield solutions with minute, and often null, duality gaps for instances with several hundreds of points in small computation times. To our knowledge, this is the first computational study ever reported in which these three stabbing problems are considered and where provably optimal solutions are given. © 2014 EDP Sciences, ROADEF, SMAI.The problem of finding structures with minimum stabbing number has received considerable attention from researchers. Particularly, [10] study the minimum stabbing number of perfect matchings (mspm), spanning trees (msst) and triangulations (mstr) associat482211233CNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTĂFICO E TECNOLĂGICOFAPESP - FUNDAĂĂO DE AMPARO Ă PESQUISA DO ESTADO DE SĂO PAULO301732/2007-8; 473867/2010-9; 147619/2010-607/52015-
Valid inequalities for a single constrained 0-1 MIP set intersected with a conflict graph
In this paper a mixed integer set resulting from the intersection of a single constrained mixed 0â1 set with the vertex packing set is investigated. This set arises as a subproblem of more general mixed integer problems such as inventory routing and facility location problems. Families of strong valid inequalities that take into account the structure of the simple mixed integer set and that of the vertex packing set simultaneously are introduced. In particular, the well-known mixed integer rounding inequality is generalized to the case where incompatibilities between binary variables are present. Exact and heuristic algorithms are designed to solve the separation problems associated to the proposed valid inequalities. Preliminary computational experiments show that these inequalities can be useful to reduce the integrality gaps and to solve integer programming problems
The Fornax Cluster through S-PLUS
The Southern Photometric Local Universe Survey (S-PLUS) aims to map â 9300 deg2of the southernsky using the Javalambre filter system of 12 optical bands, 5 Sloan-like filters and 7 narrow-band filters centeredon several prominent stellar features ([OII], Ca H+K, D4000, HÎŽ, Mgb, Hα and CaT). S-PLUS is carried outwith the T80-South, a new robotic 0.826 m telescope located on CTIO, equipped with a wide field of view camera(2 deg2). In this poster we introduce project #59 of the S-PLUS collaboration aimed at studying the Fornaxgalaxy cluster covering an sky area of â 11 Ă 7 deg2, and with homogeneous photometry in the 12 optical bandsof S-PLUS (Coordinator: A. Smith Castelli).Fil: Smith Castelli, Analia Viviana. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - La Plata. Instituto de AstrofĂsica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias AstronĂłmicas y GeofĂsicas. Instituto de AstrofĂsica La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias AstronĂłmicas y GeofĂsicas; ArgentinaFil: Mendez de Olivera, C.. Universidade do Sao Paulo. Instituto de Astronomia, GeofĂsica e CiĂȘncias AtmosfĂ©ricas; BrasilFil: Herpic, F.. Universidade do Sao Paulo. Instituto de Astronomia, GeofĂsica e CiĂȘncias AtmosfĂ©ricas; BrasilFil: Barbosa, C.. Universidade do Sao Paulo. Instituto de Astronomia, GeofĂsica e CiĂȘncias AtmosfĂ©ricas; BrasilFil: Escudero, Carlos Gabriel. Universidad Nacional de La Plata. Facultad de Ciencias AstronĂłmicas y GeofĂsicas; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - La Plata. Instituto de AstrofĂsica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias AstronĂłmicas y GeofĂsicas. Instituto de AstrofĂsica La Plata; ArgentinaFil: Grossi, M.. Observatorio de Valongo; BrasilFil: SodrĂ©, L.. Universidade do Sao Paulo. Instituto de Astronomia, GeofĂsica e CiĂȘncias AtmosfĂ©ricas; BrasilFil: de Bom, .. Centro Brasileiro de Pesquisas FĂsicas; BrasilFil: Zenocratti, Lucas JesĂșs. Universidad Nacional de La Plata. Facultad de Ciencias AstronĂłmicas y GeofĂsicas; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - La Plata. Instituto de AstrofĂsica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias AstronĂłmicas y GeofĂsicas. Instituto de AstrofĂsica La Plata; ArgentinaFil: de Rossi, Maria Emilia. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Ciudad Universitaria. Instituto de AstronomĂa y FĂsica del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de AstronomĂa y FĂsica del Espacio; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Ciudad Universitaria. Instituto de AstronomĂa y FĂsica del Espacio(i); ArgentinaFil: Cortesi, A.. Observatorio de Valongo; BrasilFil: Cid Fernandes, R.. Universidade Federal de Santa Catarina; BrasilFil: Lopes, A.. Ministerio de Ciencia, TecnologĂa E Innovacao. Observatorio Nacional. Departamento Astronomia y AstrofĂsica; BrasilFil: Telles, E.. MinistĂ©rio de Ciencia, Tecnologia e Innovacao. Observatorio Nacional; BrasilFil: Oliveira Schwarz, G. B.. Universidade Anhembi Morumbi; BrasilFil: Dantas, M. L. L.. Nicolaus Copernicus Astronomical Center; PoloniaFil: Faifer, Favio RaĂșl. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - La Plata. Instituto de AstrofĂsica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias AstronĂłmicas y GeofĂsicas. Instituto de AstrofĂsica La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias AstronĂłmicas y GeofĂsicas; ArgentinaFil: Chies Santos, A.. Universidade Federal de Santa Catarina; BrasilFil: Saponara, Juliana. Provincia de Buenos Aires. GobernaciĂłn. ComisiĂłn de Investigaciones CientĂficas. Instituto Argentino de RadioastronomĂa. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - La Plata. Instituto Argentino de RadioastronomĂa; ArgentinaFil: Reynaldi, MarĂa Victoria. Universidad Nacional de La Plata. Facultad de Ciencias AstronĂłmicas y GeofĂsicas; ArgentinaFil: Andruchow, Ileana. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - La Plata. Instituto de AstrofĂsica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias AstronĂłmicas y GeofĂsicas. Instituto de AstrofĂsica La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias AstronĂłmicas y GeofĂsicas; ArgentinaFil: Sesto, Leandro Alberto. Universidad Nacional de La Plata. Facultad de Ciencias AstronĂłmicas y GeofĂsicas; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - La Plata. Instituto de AstrofĂsica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias AstronĂłmicas y GeofĂsicas. Instituto de AstrofĂsica La Plata; ArgentinaFil: Mestre, M.. Universidad Nacional de La Plata. Facultad de Ciencias AstronĂłmicas y GeofĂsicas; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - La Plata. Instituto de AstrofĂsica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias AstronĂłmicas y GeofĂsicas. Instituto de AstrofĂsica La Plata; ArgentinaFil: de Amorim, A. L.. Universidade Federal de Santa Catarina; BrasilFil: de Lima, E. V. R.. Universidade do Sao Paulo. Instituto de Astronomia, GeofĂsica e CiĂȘncias AtmosfĂ©ricas; BrasilFil: Abboud, J.. Universidade do Sao Paulo. Instituto de Astronomia, GeofĂsica e CiĂȘncias AtmosfĂ©ricas; BrasilFil: Cernic, V.. Universidade do Sao Paulo. Instituto de Astronomia, GeofĂsica e CiĂȘncias AtmosfĂ©ricas; BrasilFil: Souza de Almeida Garcia, I.. Universidade do Sao Paulo. Instituto de Astronomia, GeofĂsica e CiĂȘncias AtmosfĂ©ricas; Brasil62° ReuniĂłn Anual de la AsociaciĂłn Argentina de AstronomĂaRosarioArgentinaUniversidad Nacional de RosarioComplejo AstronĂłmico Municipal Galileo Galile
Differential branching fraction and angular analysis of the decay B0âKâ0ÎŒ+ÎŒâ
The angular distribution and differential branching fraction of the decay B 0â K â0 ÎŒ + ÎŒ â are studied using a data sample, collected by the LHCb experiment in pp collisions at sâ=7 TeV, corresponding to an integrated luminosity of 1.0 fbâ1. Several angular observables are measured in bins of the dimuon invariant mass squared, q 2. A first measurement of the zero-crossing point of the forward-backward asymmetry of the dimuon system is also presented. The zero-crossing point is measured to be q20=4.9±0.9GeV2/c4 , where the uncertainty is the sum of statistical and systematic uncertainties. The results are consistent with the Standard Model predictions
Measurement of the branching fraction
The branching fraction is measured in a data sample
corresponding to 0.41 of integrated luminosity collected with the LHCb
detector at the LHC. This channel is sensitive to the penguin contributions
affecting the sin2 measurement from The
time-integrated branching fraction is measured to be . This is the most precise measurement to
date
Measurement of the lifetime
Using a data set corresponding to an integrated luminosity of ,
collected by the LHCb experiment in collisions at centre-of-mass energies
of 7 and 8 TeV, the effective lifetime in the
decay mode, , is measured to be ps. Assuming
conservation, corresponds to the lifetime of the light
mass eigenstate. This is the first measurement of the effective
lifetime in this decay mode.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2016-017.htm
Observation of two new baryon resonances
Two structures are observed close to the kinematic threshold in the mass spectrum in a sample of proton-proton collision data, corresponding
to an integrated luminosity of 3.0 fb recorded by the LHCb experiment.
In the quark model, two baryonic resonances with quark content are
expected in this mass region: the spin-parity and
states, denoted and .
Interpreting the structures as these resonances, we measure the mass
differences and the width of the heavier state to be
MeV,
MeV,
MeV, where the first and second
uncertainties are statistical and systematic, respectively. The width of the
lighter state is consistent with zero, and we place an upper limit of
MeV at 95% confidence level. Relative
production rates of these states are also reported.Comment: 17 pages, 2 figure
Evidence for the strangeness-changing weak decay
Using a collision data sample corresponding to an integrated luminosity
of 3.0~fb, collected by the LHCb detector, we present the first search
for the strangeness-changing weak decay . No
hadron decay of this type has been seen before. A signal for this decay,
corresponding to a significance of 3.2 standard deviations, is reported. The
relative rate is measured to be
, where and
are the and fragmentation
fractions, and is the branching
fraction. Assuming is bounded between 0.1 and
0.3, the branching fraction would lie
in the range from to .Comment: 7 pages, 2 figures, All figures and tables, along with any
supplementary material and additional information, are available at
https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-047.htm
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