Reports de recerca
http://hdl.handle.net/2117/3973
Thu, 22 Jun 2017 14:19:32 GMT2017-06-22T14:19:32ZThe complexity of testing properties of simple games
http://hdl.handle.net/2117/103171
The complexity of testing properties of simple games
Freixas Bosch, Josep; Molinero Albareda, Xavier; Olsen, Martin; Serna Iglesias, María José
Simple games cover voting systems in which a single alternative, such as a bill or an amendment, is pitted against the status quo. A simple game or a yes-no voting system is a set of rules that specifies exactly which collections of ``yea'' votes yield passage of the issue at hand. A collection of ``yea'' voters forms a winning coalition.
We are interested on performing a complexity analysis of problems on such games depending on the game representation. We consider four natural explicit representations, winning, loosing, minimal winning, and maximal loosing. We first analyze the computational complexity of obtaining a particular representation of a simple game from a different one. We show that some cases this transformation can be done in polynomial time while the others require exponential time. The second question is classifying the complexity for testing whether a game is simple or weighted. We show that for the four types of representation both problem can be solved in polynomial time. Finally, we provide results on the complexity of testing whether a simple game or a weighted game is of a special type. In this way, we analyze strongness, properness, decisiveness and homogeneity, which are desirable properties to be fulfilled for a simple game.
Fri, 31 Mar 2017 15:48:07 GMThttp://hdl.handle.net/2117/1031712017-03-31T15:48:07ZFreixas Bosch, JosepMolinero Albareda, XavierOlsen, MartinSerna Iglesias, María JoséSimple games cover voting systems in which a single alternative, such as a bill or an amendment, is pitted against the status quo. A simple game or a yes-no voting system is a set of rules that specifies exactly which collections of ``yea'' votes yield passage of the issue at hand. A collection of ``yea'' voters forms a winning coalition.
We are interested on performing a complexity analysis of problems on such games depending on the game representation. We consider four natural explicit representations, winning, loosing, minimal winning, and maximal loosing. We first analyze the computational complexity of obtaining a particular representation of a simple game from a different one. We show that some cases this transformation can be done in polynomial time while the others require exponential time. The second question is classifying the complexity for testing whether a game is simple or weighted. We show that for the four types of representation both problem can be solved in polynomial time. Finally, we provide results on the complexity of testing whether a simple game or a weighted game is of a special type. In this way, we analyze strongness, properness, decisiveness and homogeneity, which are desirable properties to be fulfilled for a simple game.Identifiability and transportability in dynamic causal networks
http://hdl.handle.net/2117/101979
Identifiability and transportability in dynamic causal networks
Blondel, Gilles; Arias Vicente, Marta; Gavaldà Mestre, Ricard
In this paper we propose a causal analog to the purely observational Dynamic Bayesian Networks, which we call Dynamic Causal Networks.
We provide a sound and complete algorithm for identification of Dynamic Causal Networks, namely, for computing the effect of an intervention or experiment, based on passive observations only, whenever possible. We note the existence of two types of confounder variables that affect in substantially different ways the identification
procedures, a distinction with no analog in either Dynamic Bayesian Networks or standard causal graphs. We further propose a procedure
for the transportability of causal effects in Dynamic Causal Network settings, where the result of causal experiments in a source domain may be used for the identification of causal effects in a target domain.
Mon, 06 Mar 2017 16:15:45 GMThttp://hdl.handle.net/2117/1019792017-03-06T16:15:45ZBlondel, GillesArias Vicente, MartaGavaldà Mestre, RicardIn this paper we propose a causal analog to the purely observational Dynamic Bayesian Networks, which we call Dynamic Causal Networks.
We provide a sound and complete algorithm for identification of Dynamic Causal Networks, namely, for computing the effect of an intervention or experiment, based on passive observations only, whenever possible. We note the existence of two types of confounder variables that affect in substantially different ways the identification
procedures, a distinction with no analog in either Dynamic Bayesian Networks or standard causal graphs. We further propose a procedure
for the transportability of causal effects in Dynamic Causal Network settings, where the result of causal experiments in a source domain may be used for the identification of causal effects in a target domain.Measuring satisfaction in societies with opinion leaders and mediators
http://hdl.handle.net/2117/101810
Measuring satisfaction in societies with opinion leaders and mediators
Molinero Albareda, Xavier; Riquelme Csori, F.; Serna Iglesias, María José
An opinion leader-follower model (OLF) is a two-action collective decision-making model for societies, in which three kinds of actors are considered:
Wed, 01 Mar 2017 16:19:14 GMThttp://hdl.handle.net/2117/1018102017-03-01T16:19:14ZMolinero Albareda, XavierRiquelme Csori, F.Serna Iglesias, María JoséAn opinion leader-follower model (OLF) is a two-action collective decision-making model for societies, in which three kinds of actors are considered:Informe sobre la Competència de Sostenibilitat i Compromís Social a la Universitat Politècnica Catalunya
http://hdl.handle.net/2117/100975
Informe sobre la Competència de Sostenibilitat i Compromís Social a la Universitat Politècnica Catalunya
Hernández Gómez, M. Angeles; Sureda Carbonell, Bàrbara; Escribano Rodríguez de Robles, Beatriz; Carrera Gallissà, Enric; Martínez Magaña, Juan; Aguado Chao, Juan Carlos; Cot Valle, María Ana; Busquets Rubio, Pere
Tue, 14 Feb 2017 12:52:01 GMThttp://hdl.handle.net/2117/1009752017-02-14T12:52:01ZHernández Gómez, M. AngelesSureda Carbonell, BàrbaraEscribano Rodríguez de Robles, BeatrizCarrera Gallissà, EnricMartínez Magaña, JuanAguado Chao, Juan CarlosCot Valle, María AnaBusquets Rubio, PereGeneralising discontinuity
http://hdl.handle.net/2117/100910
Generalising discontinuity
Morrill, Glyn; Merenciano Saladrigas, Josep Maria
This paper makes two generalisations of categorial calculus of discontinuity. In the first we introduce unary modalities which mediate between continuous and discontinuous strings. In the second each of the modes of adjunction of the proposal to date, concatenation, juxtaposition and interpolation, are augmented with variants. Linguistic illustration and motivation is provided, and we show how adherence to a discipline of sorting renders the generalisations tractable within a particularly efficient logic programming paradigm.
Mon, 13 Feb 2017 11:51:52 GMThttp://hdl.handle.net/2117/1009102017-02-13T11:51:52ZMorrill, GlynMerenciano Saladrigas, Josep MariaThis paper makes two generalisations of categorial calculus of discontinuity. In the first we introduce unary modalities which mediate between continuous and discontinuous strings. In the second each of the modes of adjunction of the proposal to date, concatenation, juxtaposition and interpolation, are augmented with variants. Linguistic illustration and motivation is provided, and we show how adherence to a discipline of sorting renders the generalisations tractable within a particularly efficient logic programming paradigm.A graph semantics for a variant of the ambient calculus more adequate for modeling SOC
http://hdl.handle.net/2117/100667
A graph semantics for a variant of the ambient calculus more adequate for modeling SOC
Mylonakis Pascual, Nicolás
In this paper we present a graph semantics of a variant of the well known ambient calculus. The main change of our variant is to extract the mobility commands of the original calculus from the ambient topology. Similar to a previous work of ours, we prove that our encoding have good properties. We strongly believe that this variant would allow us to integrate our graph semantics of our mobile calculus with previous work of us in service oriented computing (SOC). Basically, our work on SOC develops a new graph transformation system which we call temporal symbolic graphs. This new graph formalism is used to give semantics to a design language for SOC developed in an european
project, but it could also be used in connection with other approaches for modeling or specifying service systems.
Wed, 08 Feb 2017 11:06:00 GMThttp://hdl.handle.net/2117/1006672017-02-08T11:06:00ZMylonakis Pascual, NicolásIn this paper we present a graph semantics of a variant of the well known ambient calculus. The main change of our variant is to extract the mobility commands of the original calculus from the ambient topology. Similar to a previous work of ours, we prove that our encoding have good properties. We strongly believe that this variant would allow us to integrate our graph semantics of our mobile calculus with previous work of us in service oriented computing (SOC). Basically, our work on SOC develops a new graph transformation system which we call temporal symbolic graphs. This new graph formalism is used to give semantics to a design language for SOC developed in an european
project, but it could also be used in connection with other approaches for modeling or specifying service systems.A multi-projector CAVE system with commodity hardware and gesture-based interaction
http://hdl.handle.net/2117/99668
A multi-projector CAVE system with commodity hardware and gesture-based interaction
Andújar Gran, Carlos Antonio; Brunet Crosa, Pere; Vinacua Pla, Álvaro; Vico Moya, Miguel Ángel; Díaz García, Jesús
Spatially-immersive systems such as CAVEs provide users with surrounding worlds by projecting 3D models on multiple screens around the viewer. Compared to alternative immersive systems such as HMDs, CAVE systems are a powerful tool for collaborative inspection of virtual environments due to better use of peripheral vision, less sensitivity to tracking errors, and higher communication possibilities among users. Unfortunately, traditional CAVE setups require sophisticated equipment including stereo-ready projectors and tracking systems with high acquisition and maintenance costs. In this paper we present the design and construction of a passive-stereo, four-wall CAVE system based on commodity hardware. Our system works with any mix of a wide range of projector models that can be replaced independently at any time, and achieves high resolution and brightness at a minimum cost. The key ingredients of our CAVE are a self-calibration approach that guarantees continuity across the screen, as well as a gesture-based interaction approach based on a clever
combination of skeletal data from multiple Kinect sensors.
Thu, 19 Jan 2017 11:55:25 GMThttp://hdl.handle.net/2117/996682017-01-19T11:55:25ZAndújar Gran, Carlos AntonioBrunet Crosa, PereVinacua Pla, ÁlvaroVico Moya, Miguel ÁngelDíaz García, JesúsSpatially-immersive systems such as CAVEs provide users with surrounding worlds by projecting 3D models on multiple screens around the viewer. Compared to alternative immersive systems such as HMDs, CAVE systems are a powerful tool for collaborative inspection of virtual environments due to better use of peripheral vision, less sensitivity to tracking errors, and higher communication possibilities among users. Unfortunately, traditional CAVE setups require sophisticated equipment including stereo-ready projectors and tracking systems with high acquisition and maintenance costs. In this paper we present the design and construction of a passive-stereo, four-wall CAVE system based on commodity hardware. Our system works with any mix of a wide range of projector models that can be replaced independently at any time, and achieves high resolution and brightness at a minimum cost. The key ingredients of our CAVE are a self-calibration approach that guarantees continuity across the screen, as well as a gesture-based interaction approach based on a clever
combination of skeletal data from multiple Kinect sensors.Projecte Inspira'ns: detecció d'idees relacionades
http://hdl.handle.net/2117/99488
Projecte Inspira'ns: detecció d'idees relacionades
Vigo, M.
El projecte Inspira'ns compta amb un sistema online per a la recollida de suggeriments i comentaris (Idea) d'usuaris. Aquests comentaris es classifiquen per categories (Aplicacions mòbils, Banca mòbil, Banca per Internet, Caixers i Targetes), i pels temes que tracten (el tema és lliure, generalment es tracta de peticions de millora d'un servei o problemes detectats amb algun producte o servei, entre d'altres). Sovint els usuaris es refereixen a una mateixa Idea, és a dir, es reben suggeriments i comentaris repetits. Actualment, la classificació d'aquestes idees es duu a terme de forma manual. L'objectiu d'aquest projecte és desenvolupar una metodologia que permeti detectar que una nova Idea és similar a una Idea anterior rebuda. És a dir, donat un conjunt D d'idees, determinar si una nova Idea d està relacionada (és similar) amb alguna de les idees del conjunt D.
Tue, 17 Jan 2017 14:03:35 GMThttp://hdl.handle.net/2117/994882017-01-17T14:03:35ZVigo, M.El projecte Inspira'ns compta amb un sistema online per a la recollida de suggeriments i comentaris (Idea) d'usuaris. Aquests comentaris es classifiquen per categories (Aplicacions mòbils, Banca mòbil, Banca per Internet, Caixers i Targetes), i pels temes que tracten (el tema és lliure, generalment es tracta de peticions de millora d'un servei o problemes detectats amb algun producte o servei, entre d'altres). Sovint els usuaris es refereixen a una mateixa Idea, és a dir, es reben suggeriments i comentaris repetits. Actualment, la classificació d'aquestes idees es duu a terme de forma manual. L'objectiu d'aquest projecte és desenvolupar una metodologia que permeti detectar que una nova Idea és similar a una Idea anterior rebuda. És a dir, donat un conjunt D d'idees, determinar si una nova Idea d està relacionada (és similar) amb alguna de les idees del conjunt D.h-graphs: A new representation for tree decompositions of graphs
http://hdl.handle.net/2117/99483
h-graphs: A new representation for tree decompositions of graphs
Hidalgo Garcia, Marta; Joan Arinyo, Robert
In geometric constraint solving, well constrained geometric problems can be abstracted as Laman graphs. If the graph is tree decomposable, the constraint-based geometric problem can be solved by a Decomposition-Recombination planner based solver. In general decomposition and recombination steps can be completed only when other steps have already been completed. This fact naturally defines a hierarchy in the decomposition-recombination steps that traditional tree decomposition representations do not capture explicitly. In this work we introduce h-graphs, a new representation for decompositions of tree decomposable Laman graphs, which captures dependence relations between different tree decomposition steps. We show how h-graphs help in efficiently computing parameter ranges for which solution instances to well constrained, tree decomposable geometric constraint problems with one degree of freedom can actually be constructed.
Tue, 17 Jan 2017 13:41:49 GMThttp://hdl.handle.net/2117/994832017-01-17T13:41:49ZHidalgo Garcia, MartaJoan Arinyo, RobertIn geometric constraint solving, well constrained geometric problems can be abstracted as Laman graphs. If the graph is tree decomposable, the constraint-based geometric problem can be solved by a Decomposition-Recombination planner based solver. In general decomposition and recombination steps can be completed only when other steps have already been completed. This fact naturally defines a hierarchy in the decomposition-recombination steps that traditional tree decomposition representations do not capture explicitly. In this work we introduce h-graphs, a new representation for decompositions of tree decomposable Laman graphs, which captures dependence relations between different tree decomposition steps. We show how h-graphs help in efficiently computing parameter ranges for which solution instances to well constrained, tree decomposable geometric constraint problems with one degree of freedom can actually be constructed.Firefighting as a Game
http://hdl.handle.net/2117/99479
Firefighting as a Game
Álvarez Faura, M. del Carme; Blesa Aguilera, Maria Josep; Molter, Hendrik
The Firefighter Problem was proposed in 1995 [16] as a deterministic discrete-time model for the spread (and containment) of a fire. Its applications reach from real fires to the spreading of deseases and the containment of floods. Furthermore, it can be used to model the spread of computer viruses or viral marketing in communication networks. In this work, we study the problem from a game-theorical perspective. Such a context seems very appropriate when applied to large networks, where entities may act and make decisions based on their own interests, without global coordination. We model the Firefighter Problem as a strategic game where there is one player for each time step who decides where to place the firefighters. We show that the Price of Anarchy is linear in the general case, but at most 2 for trees. We prove that the quality of the equilibria improves when allowing coalitional cooperation among players. In general, we have that the Price of Anarchy is in O( n / k ) where k is the coalition size. Furthermore, we show that there are topologies which have a constant Price of Anarchy even when constant sized coalitions are considered.
Tue, 17 Jan 2017 13:25:59 GMThttp://hdl.handle.net/2117/994792017-01-17T13:25:59ZÁlvarez Faura, M. del CarmeBlesa Aguilera, Maria JosepMolter, HendrikThe Firefighter Problem was proposed in 1995 [16] as a deterministic discrete-time model for the spread (and containment) of a fire. Its applications reach from real fires to the spreading of deseases and the containment of floods. Furthermore, it can be used to model the spread of computer viruses or viral marketing in communication networks. In this work, we study the problem from a game-theorical perspective. Such a context seems very appropriate when applied to large networks, where entities may act and make decisions based on their own interests, without global coordination. We model the Firefighter Problem as a strategic game where there is one player for each time step who decides where to place the firefighters. We show that the Price of Anarchy is linear in the general case, but at most 2 for trees. We prove that the quality of the equilibria improves when allowing coalitional cooperation among players. In general, we have that the Price of Anarchy is in O( n / k ) where k is the coalition size. Furthermore, we show that there are topologies which have a constant Price of Anarchy even when constant sized coalitions are considered.