343 research outputs found
Online Coalition Formation under Random Arrival or Coalition Dissolution
Coalition formation considers the question of how to partition a set of
agents into disjoint coalitions according to their preferences. We consider a
cardinal utility model with additively separable aggregation of preferences and
study the online variant of coalition formation, where the agents arrive in
sequence and whenever an agent arrives, they have to be assigned to a coalition
immediately. The goal is to maximize social welfare. In a purely deterministic
model, the greedy algorithm, where an agent is assigned to the coalition with
the largest gain, is known to achieve an optimal competitive ratio, which
heavily relies on the range of utilities.
We complement this result by considering two related models. First, we study
a model where agents arrive in a random order. We find that the competitive
ratio of the greedy algorithm is , whereas an
alternative algorithm, which is based on alternating between waiting and greedy
phases, can achieve a competitive ratio of .
Second, we relax the irrevocability of decisions by allowing to dissolve
coalitions into singleton coalitions, presenting a matching-based algorithm
that once again achieves a competitive ratio of
. Hence, compared to the base model, we present
two ways to achieve a competitive ratio that precisely gets rid of utility
dependencies. Our results also give novel insights in weighted online matching.Comment: Appears in the 31st Annual European Symposium on Algorithms (ESA
2023
Structure of Spin Correlations in High Temperature SU() Quantum Magnets
Quantum magnets with a large SU() symmetry are a promising playground for
the discovery of new forms of exotic quantum matter. Motivated by recent
experimental efforts to study SU() quantum magnetism in samples of ultracold
fermionic alkaline-earth-like atoms in optical lattices, we study here the
temperature dependence of spin correlations in the SU() Heisenberg spin
model in a wide range of temperatures. We uncover a sizeable regime in
temperature, starting at down to intermediate temperatures and for
all , in which the correlations have a common spatial structure on a
broad range of lattices, with the sign of the correlations alternating from one
Manhattan shell to the next, while the amplitude of the correlations is rapidly
decreasing with distance. Focussing on the one-dimensional chain and the
two-dimensional square and triangular lattice for certain , we discuss the
appearance of a disorder and a Lifshitz temperature, separating the
commensurate Manhattan high- regime from a low- incommensurate regime. We
observe that this temperature window is associated to an approximately
-independent entropy reduction from the entropy at infinite
temperature. Our results are based on high-temperature series arguments and as
well as large-scale numerical full diagonalization results of thermodynamic
quantities for SU() and SU() square lattice samples, corresponding to a
total Hilbert space of up to states.Comment: 14 pages, 8 figure
Herbal Remedies for Breast Cancer Prevention and Treatment
Breast cancer is among the most common type of cancer in women around the globe. Prevention of breast cancer is better than its treatment. Because of the molecular variation and complexity underlying breast cancer occurrence, its treatment by using chemotherapy and/or radiotherapy is very complicated and often leads to undesirable side effects. Plants and their extracts have been used for centuries for the treatment of almost every disease and breast cancer is not an exception. Herbal products can be trusted for cancer treatment because of their low toxicity. Besides, herbal remedies are easily accepted by the majority of woman suffering from breast cancer because of their easy availability and affordability. In the last decade, a large number of plants and their compounds were reported to show promising anticancerous effects against breast cancer cells in both in vivo and in vitro models. However, their beneficial effects on breast cancer treatment are still doubtful due to the lack of randomized clinical trials. This chapter is dedicated to reporting the potential of some herbal products for the prevention and/or treatment of breast cancer. Besides, it focused on the anticarcinogenic mechanism of those phytocompounds to report their potential chemotherapeutic role
Procedimiento de preparación de derivados de tipo arilo-heteroarilo y arilo-arilo y compuestos obtenidos
El objeto de la presente invención es un
procedimiento de preparación de derivados de tipo
arilo — heteroarilo y arilo - arilo a partir de anilinas o
sales de diazonio y de compuestos aromáticos, que
pueden ser arilos o heteroarilo, en el cual se utilizan
materiales que aportan ácido ascórbico o sus
derivados como catalizadores.
Constituyen igualmente un objeto de la presente
invención los compuestos obtenidos mediante el
referido procedimiento.Peer reviewedConsejo Superior de Investigaciones CientíficasA1 Solicitud de adición a la patent
La protección del derecho del propietario de la vivienda frente a la okupación
The Spanish Constitution recognizes the right of home, but this right does not
entail a legal obligation for the owners to bear the dispossession of their property to
guarantee the right against those who do not have any, and much less, in an illegitimate
way as it is happening, frequently, in this country with the so-called squatting
phenomenon. Each year exceeds the previous one, with respect to the number of
properties that have been squatted, that is, the owner's possession was taken from the
squatter, illegally. Faced with this, the owner can defend himself both through civil and
criminal proceedings, either through actual actions, filing a lawsuit, or through a
complaint, if the way in which the squatting was carried out constitutes a crime.
However, and despite some legislative improvements to protect the rights of the owners,
squatting continues increasing, and even more so, after the last legislative change and as
a consequence of the pandemic. All of this, and in the face of instability that generates
social discontent, has created the ideal conditions for the emergence of private
undocking companies that try to provide a solution that, legislatively, does not always
arrive.La Constitución Española reconoce el derecho a una vivienda, pero este derecho
no conlleva una obligación legal para los propietarios de soportar el despojo de su
inmueble para garantizar el derecho frente a quien no ostenta ninguno, y mucho menos,
de una manera ilegítima como está sucediendo, de forma frecuente, en este país con el
denominado fenómeno okupa. Cada año supera al anterior, respecto al número de
inmuebles que han sido okupados, es decir, arrebatada la posesión del propietario por
parte del okupa, ilegalmente. Ante ello, el propietario puede defenderse tanto por la vía
civil, como por la vía penal, ya sea mediante acciones reales, interponiendo demanda, o
mediante querella, si el modo en que la okupación fue llevada a cabo, constituye delito.
No obstante, y a pesar de algunas mejoras legislativas para proteger los derechos de los
propietarios, la okupación sigue aumentando, y más aún, tras la última modificación
legislativa y como consecuencia de la pandemia. Todo ello, y ante una inestabilidad que
genera descontento social, ha propiciado las condiciones idóneas para la aparición de
empresas privadas de desokupación que intentan dar una solución que, legislativamente,
no siempre llega
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