1,932,633 research outputs found
Grouping puts figure-ground assignment in context by constraining propagation of edge assignment.
No full textFigure-ground organization involves the assignment of edges to a figural shape on one or the other side of each dividing edge. Established visual cues for edge assignment primarily concern relatively local rather than contextual factors. In the present article, we show that an assignment for a locally unbiased edge can be affected by an assignment of a remote contextual edge that has its own locally biased assignment. We find that such propagation of edge assignment from the biased remote context occurs only when the biased and unbiased edges are grouped. This new principle, whereby grouping constrains the propagation of figural edge assignment, emerges from both subjective reports and an objective short-term edge-matching task. It generalizes from moving displays involving grouping by common fate and collinearity, to static displays with grouping by similarity of edge-contrast polarity, or apparent occlusion. Our results identify a new contextual influence on edge assignment. They also identify a new mechanistic relation between grouping and figure-ground processes, whereby grouping between remote elements can constrain the propagation of edge assignment between those elements. Supplemental materials for this article may be downloaded from http://app.psychonomic-journals.org/content/supplemental
Assignment markets with the same core
No full textIn the framework of bilateral assignment games, we study the set of matrices associated with assignment markets with the same core. We state conditions on matrix entries that ensure that the related assignment games have the same core. We prove that the set of matrices leading to the same core form a join-semilattice with a nite number of minimal elements and a unique maximum. We provide a characterization of the minimal elements. A sucient condition under which the join-semilattice reduces to a lattice is also given.core, semilattice, assignment game
Assignment Situations with Multiple Ownership and their Games
No full textAn assignment situation can be considered as a two-sided market consisting of two disjoint sets of objects.A non-negative reward matrix describes the profit if an object of one group is assigned to an object of the other group. Assuming that each object is owned by a different agent, Shapley and Shubik (1972) introduced a class of assignment games arising from these assignment situations.This paper introduces assignment situations with multiple ownership. In these situations each object can be owned by several agents and each agent can participate in the ownership of more than one object.In this paper we study simple assignment games and relaxations that arise from assignment situations with multiple ownership.First, necessary and sufficient conditions are provided for balanced assignment situations with multiple ownership.An assignment situation with multiple ownership is balanced if for any choice of the reward matrix the corresponding simple assignment game is balanced.Second, balancedness results are obtained for relaxations of simple assignment games.assignment situations;matchings;assignment games;balancedness
Approximating the multi-level bottleneck assignment problem.
No full textWe consider the multi-level bottleneck assignment problem (MBA). This problem is described in the recent book 'Assignment Problems' by Burkard et al. (2009) on pages 188-189. One of the applications described there concerns bus driver scheduling.We view the problem as a special case of a bottleneck m-dimensional multi-index assignment problem. We give approximation algorithms and inapproximability results, depending upon the completeness of the underlying graph. Keywords: bottleneck problem; multidimensional assignment; approximation; computational complexity; efficient algorithm.Bottleneck problem; Multidimensional assignment; Approximation; Computational complexity; Efficient algorithm;
Complements and substitutes in multilateral assignment markets
No full textI prove that, in assignment markets with more than two sides, agents of different sides (or sectors) need not be complements, whereas agents of the same side need not be substitutes. Shapley (1962) showed that this cannot happen when assignment markets are bilateral. Nevertheless, I found sufficient conditions, that always hold for bilateral markets, that guarantee substitutability and a extended notion of complementarity among agents in arbitrary multilateral assignment markets. I also prove that Shapleys (1962) result always holds regardless the number of sectors of the market when goods in the market are homogeneous.complementarity, homogeneous goods, substitutability, assignment problem, multi-sided assignment markets
On the dimension of the core of the assignment game
No full textThe set of optimal matchings in the assignment matrix allows to define a reflexive and symmetric binary relation on each side of the market, the equal-partner binary relation. The number of equivalence classes of the transitive closure of the equal-partner binary relation determines the dimension of the core of the assignment game. This result provides an easy procedure to determine the dimension of the core directly from the entries of the assignment matrix and shows that the dimension of the core is not as much determined by the number of optimal matchings as by their relative position in the assignment matrix.core, assignment game, core dimension
The assignment game: core bounds for mixe-pair coalitions
No full textIn the assignment game framework, we try to identify those assignment matrices in which no entry can be increased without changing the core of the game. These games will be called buyerseller exact games and satisfy the condition that each mixedpair coalition attains the corresponding matrix entry in the core of the game. For a given assignment game, a unique buyerseller exact assignment game with the same core is proved to exist. In order to identify this matrix and to provide a characterization of those assignment games which are buyerseller exact in terms of the assignment matrix, attainable upper and lower core bounds for the mixedpair coalitions are found. As a consequence, an open question posed in Quint (1991) regarding a canonical representation of a 45olattice by means of the core of an assignment game can now be answered.core, exact games, assignment game
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The assignment game: core bounds for mixed-pair coalitions
No full textIn the assignment game framework, we try to identify those assignment matrices in which no entry can be increased without changing the coreof the game. These games will be called buyer¿seller exact games and satisfy the condition that each mixed¿pair coalition attains the corresponding matrix entry in the core of the game. For a given assignment game, a unique buyerseller exact assignment game with the same core is proved to exist. In order to identify this matrix and to provide a characterization of those assignment games which are buyer¿seller exact in terms of the assignment matrix, attainable upper and lower core bounds for the mixed¿pair coalitions are found. As a consequence, an open question posed in Quint (1991) regarding a canonical representation of a ¿45o¿lattice¿ by means of the core of an assignment game can now be answeredAquest treball tracta de determinar aquells jocs d'assignació la matriu associada dels quals té la propietat que cap de les seves entrades pot ser incrementada sense modificar el core del joc. Els anomenarem jocs d'assignació "buyer-seller" exactes ja que tota coalició comprador-venedor assoleix el pagament indicat por la seva corresponent entrada de la matriu en una distribució del core. Donat qualsevol joc d'assignació, provem l'existència d'un únic joc
d¿assignació amb el seu mateix core i amb la propietat de ser "buyer-seller" exacte. Per tal de trobar la matriu d'aquest nou joc i de caracteritzar, en termes de la matriu, els jocs d¿assignació que són "buyer-seller" exactes, fites
assolibles per al pagament de les coalicions comprador-venedor dins del core han estat calculades. Com a conseqüència podem tancar una qüestió oberta per Quint (1991) referent a la representació canònica dels reticles de 45o per
mitjà del core d'un joc d'assignació
Robust pole assignment techniques via state feedback
No full textWe present a unifying computational framework to solve robust pole assignment problems for linear systems using state feedback. The new framework uses Sylvester equation based parametrizations of the pole assignment problems. The non-uniqueness of solutions is exploited by minimizing additionally sensitivity of closed-loop eigenvalues and the norm of the corresponding state feedback matrix. The solution methods rely on using gradient search based minimization techniques on suitably defined cost functions. The discussion of main functional and numerical aspects reveals many desirable features of the underlying algorithms which recommend them to serve as bases for robust numerical software implementations
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