Fusión de modelos vectoriales y contextuales para la recuperación de información

El creciente volumen de documentos almacenados en ordenadores en formato electrónico promete un cambio importante en la forma de buscar cualquier tipo de información. Este cambio ya se está produciendo, en parte debido a Internet, pero también por la existencia de cada vez más sistemas cuyo fin es proporcionar información de diferentes tipos y que se utilizan de forma creciente en prácticamente todas las esferas de la vida diaria. La "sociedad de la información" presenta nuevas posibilidades, pero también nuevos retos para la informática. Es necesario superar las dificultades relacionadas con la búsqueda de información relevante sobre cualquier tema, sea la fuente Internet u otro "almacén electrónico" y, sea ésta textual, multimedia o de cualquier otro tipo. La presente tesis tiene por objetivo contribuir a superar estas dificultades y para ello analiza nuevos métodos para la recuperación de documentos de texto. En la primera parte se presenta un nuevo modelo para la recuperación de información textual: el Modelo de Vectores de Contexto (MVC). Este modelo utiliza una representación semánticamente enriquecida de los documentos y preguntas y, por tanto, la estimación de la relevancia de un documento para una pregunta se basa en una comparación de los contenidos conceptuales de estas entidades. El modelo es evaluado mediante una serie de experimentos con cuatro colecciones de prueba (MEDLARS, CRANFIELD, CISI y CACM) en los que se comparan los resultados de distintas variantes del MVC con el Modelo Vectorial (MV) clásico. No obstante, una de las principales conclusiones de los experimentos es que, aunque existen variantes del MVC que incrementan la efectividad respecto al MV de forma estadísticamente significativa en las cuatro colecciones, en cada colección hay otra variante que logra los mejores resultados. La segunda parte de esta tesis examina el comportamiento de estrategias de recuperación que combinan o fusionan variantes (expertos) del MVC y del modelo vectorial clásico. Un problema común de los métodos de fusión de expertos de recuperación es la selección, tanto de los expertos a combinar, como de la función de combinación. En la mayoría de los estudios, los expertos son "fijos" o preseleccionados mediante algunas heurísticas. Ello implica que sólo se considera un número reducido de posibles combinaciones. En este trabajo, se presenta un método que utiliza algoritmos genéticos para encontrar, de forma automática, una estrategia que sea apropiada para un determinado entorno de recuperación. El método se evalúa mediante experimentos con las cuatro colecciones de prueba citadas anteriormente. Las conclusiones principales son las siguientes: 1.- Una combinación de expertos puede ser más efectiva que los métodos individuales. 2.- La adaptación de las estrategias de recuperación a cada colección es mejor que el uso de estrategias "fijas". 3.- Los algoritmos genéticos son apropiados para el encontrar estrategias de recuperación (sub)óptimas

A context vector model for information retrieval

In the vector space model for information retrieval, term vectors are pair-wise orthogonal, that is, terms are assumed to be independent. It is well known that this assumption is too restrictive. In this article, we present our work on an indexing and retrieval method that, based on the vector space model, incorporates term dependencies and thus obtains semantically richer representations of documents. First, we generate term context vectors based on the co-occurrence of terms in the same documents. These vectors are used to calculate context vectors for documents. We present different techniques for estimating the dependencies among terms. We also define term weights that can be employed in the model. Experimental results on four text collections (MED, CRANFIELD, CISI, and CACM) show that the incorporation of term dependencies in the retrieval process performs statistically significantly better than the classical vector space model with IDF weights. We also show that the degree of semantic matching versus direct word matching that performs best varies on the four collections. We conclude that the model performs well for certain types of queries and, generally, for information tasks with high recall requirements. Therefore, we propose the use of the context vector model in combination with other, direct word-matching methods.Publicad

Demand-Responsive Shared Transportation: A Self-Interested Proposal

[EN] With the world population highly increasing, efficient methods of transportation are more necessary than ever. On the other hand, the sharing economy must be explored and applied where possible, aiming to palliate the effects of human development on the environment. In this paper we explore demand-responsive shared transportation as a system with the potential to serve its users' displacement needs while being less polluting. In contrast with previous works, we focus on a distributed proposal that allows each vehicle to retain its private information. Our work describes a partially dynamic system in which the vehicles are self-interested: they decide which users to serve according to the benefit it reports them. With our modelling, the system can be adapted to mobility platforms of autonomous drivers and even simulate the competition among different companies.This work is partially supported by grant RTI2018-095390-B-C31 funded by MCIN/AEI/10.13039/501100011033 and by "ERDF A way of making Europe". Pasqual Marti is supported by grant ACIF/2021/259 funded by the "Conselleria de Innovacion, Universidades, Ciencia y Sociedad Digital de la Generalitat Valenciana".Martí, P.; Jordán, J.; De La Prieta, F.; Billhardt, H.; Julian, V. (2022). Demand-Responsive Shared Transportation: A Self-Interested Proposal. Electronics. 11(1):1-14. https://doi.org/10.3390/electronics1101007811411

Taxi dispatching strategies with compensations

[EN] Urban mobility efficiency is of utmost importance in big cities. Taxi vehicles are key elements in daily traffic activity. The advance of ICT and geo-positioning systems has given rise to new opportunities for improving the efficiency of taxi fleets in terms of waiting times of passengers, cost and time for drivers, traffic density, CO2 emissions, etc., by using more informed, intelligent dispatching. Still, the explicit spatial and temporal components, as well as the scale and, in particular, the dynamicity of the problem of pairing passengers and taxis in big towns, render traditional approaches for solving standard assignment problem useless for this purpose, and call for intelligent approximation strategies based on domain-specific heuristics. Furthermore, taxi drivers are often autonomous actors and may not agree to participate in assignments that, though globally efficient, may not be sufficently beneficial for them individually. This paper presents a new heuristic algorithm for taxi assignment to customers that considers taxi reassignments if this may lead to globally better solutions. In addition, as such new assignments may reduce the expected revenues of individual drivers, we propose an economic compensation scheme to make individually rational drivers agree to proposed modifications in their assigned clients. We carried out a set of experiments, where several commonly used assignment strategies are compared to three different instantiations of our heuristic algorithm. The results indicate that our proposal has the potential to reduce customer waiting times in fleets of autonomous taxis, while being also beneficial from an economic point of view.This work was supported by the Autonomous Region of Madrid (grant "MOSI-AGIL-CM" (S2013/ICE-3019) co-funded by EU Structural Funds FSE and FEDER), project "SURF" (TIN2015-65515-C4-X-R (MINECO/FEDER)) funded by the Spanish Ministry of Economy and Competitiveness, and through the Excellence Research Group GES2ME (Ref. 30VCPIGI05) co-funded by URJC and Santander Bank.Billhardt, H.; Fernandez Gil, A.; Ossowski, S.; Palanca Cámara, J.; Bajo, J. (2019). Taxi dispatching strategies with compensations. Expert Systems with Applications. 122:173-182. https://doi.org/10.1016/j.eswa.2019.01.001S17318212

Dynamic coordination in fleet management systems: Toward smart cyber fleets

Fleet management systems are commonly used to coordinate mobility and delivery services in a broad variety of domains. However, their traditional top-down control architecture becomes a bottleneck in open and dynamic environments, where scalability, proactiveness, and autonomy are becoming key factors for their success. Here, the authors present an abstract event-based architecture for fleet management systems that supports tailoring dynamic control regimes for coordinating fleet vehicles, and illustrate it for the case of medical emergency management. Then, they go one step ahead in the transition toward automatic or driverless fleets, by conceiving fleet management systems in terms of cyber-physical systems, and putting forward the notion of cyber fleets. © 2014 IEEE.This work has been partially supported by the Spanish Ministry of Economy and Competitiveness through the projects “Agreement Technologies” (grant CSD2007-0022; CONSOLIDER-INGENIO 2010), “intelligent Human-Agent Societies” (grant TIN2012-36586-C03-02), and “Smart Delivery” (grant RTC-2014-1850-4).Peer Reviewe

Easy Development and Use of Dialogue Services

The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-319-07596-9_9We present a framework for Dialogue-Based Web Services (DBWS), i.e. services that require several message exchanges during their execution. Service development is simplified with the use of script languages and abstracting the communication layer. Service advertisements are carried out with a semantic Web Service directory with search and reputation capabilities. Execution can be performed from a mobile user interface that includes capabilities for user assistance. Our framework aims at filling the gap between services and non-IT users/experts. An example illustrates our proposal.Work partially supported by the Spanish Ministry of Science and Innovation through the project ”AT” (grant CSD2007-0022; CONSOLIDER-INGENIO 2010) and by the Spanish Ministry of Economy and Competitiveness through the project iHAS (grant TIN2012-36586-C03-01/02/03).Durán, JJ.; Fernández, A.; Rodríguez, S.; Julian Inglada, VJ.; Billhardt, H. (2014). Easy Development and Use of Dialogue Services. En Ambient Intelligence - Software and Applications. Springer. 81-88. https://doi.org/10.1007/978-3-319-07596-9_9S8188Guinard, D., Ion, I., Mayer, S.: In search of an internet of things service architecture: REST or WS-*? A developers’ perspective. In: Puiatti, A., Gu, T. (eds.) MobiQuitous 2011. LNICST, vol. 104, pp. 326–337. Springer, Heidelberg (2012)Pautasso, C., Zimmermann, O., Leymann, F.: Rest- ful web services vs. ”big’” web services: Making the right architectural decision. In: Proceedings of the 17th International Conference on World Wide Web, WWW 2008, pp. 805–814. ACM (2008)Lawton, G.: Developing software online with platform-as-a- service technology. Computer 41(6), 13–15 (2008)Kopel, M., Sobecki, J., Wasilewski, A.: Automatic web-based user interface delivery for soa-based systems. In: Bǎdicǎ, C., Nguyen, N.T., Brezovan, M. (eds.) ICCCI 2013. LNCS, vol. 8083, pp. 110–119. Springer, Heidelberg (2013)Bartolini, C., Bertolino, A., Marchetti, E., Polini, A.: Ws-taxi: A wsdl-based testing tool for web services. In: International Conference on Software Testing Verification and Validation, ICST 2009, pp. 326–335 (2009)Fernandez, A., Cong, Z., Balta, A.: Bridging the gap between service description models in service matchmaking. Multiagent and Grid Systems 8(1), 83–103 (2012)Hermoso, R., Billhardt, H., Centeno, R., Ossowski, S.: Effective use of organisational abstractions for confidence models. In: O’Hare, G.M.P., Ricci, A., O’Grady, M.J., Dikenelli, O. (eds.) ESAW 2006. LNCS (LNAI), vol. 4457, pp. 368–383. Springer, Heidelberg (2007

Towards smart open dynamic fleets

The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-319-33509-4_32Nowadays, vehicles of modern fleets are endowed with advanced devices that allow the operators of a control center to have global knowledge about fleet status, including existing incidents. Fleet management systems support real-time decision making at the control center so as to maximize fleet perform‐ ance. In this paper, setting out from our experience in dynamic coordination of fleet management systems, we focus on fleets that are open, dynamic and highly autonomous. Furthermore, we propose how to cope with the scalability problem as the number of vehicles grows. We present our proposed architecture for open fleet management systems and use the case of taxi services as example of our proposal.Work partially supported by Spanish Government through the projects iHAS (grant TIN2012-36586-C03) and SURF (grant TIN2015-65515-C4-X-R), the Autonomous Region of Madrid through grant S2013/ICE-3019 (“MOSI-AGIL-CM”, cofunded by EU Structural Funds FSE and FEDER) and URJC-Santander (30VCPIGI15).Billhardt, H.; Fernández, A.; Lujak, M.; Ossowski, S.; Julian Inglada, VJ.; Paz, JFD.; Hernández, JZ. (2016). Towards smart open dynamic fleets. En Multi-Agent Systems and Agreement Technologies. Springer. 410-424. https://doi.org/10.1007/978-3-319-33509-4_32S41042

Designing a goal-oriented smart-home environment

Nowadays, systems are growing in power and in access to more resources and services. This situation makes it necessary to provide user-centered systems that act as intelligent assistants. These systems should be able to interact in a natural way with human users and the environment and also be able to take into account user goals and environment information and changes. In this paper, we present an architecture for the design and development of a goal-oriented, self-adaptive, smart-home environment. With this architecture, users are able to interact with the system by expressing their goals which are translated into a set of agent actions in a way that is transparent to the user. This is especially appropriate for environments where ambient intelligence and automatic control are integrated for the user’s welfare. In order to validate this proposal, we designed a prototype based on the proposed architecture for smart-home scenarios. We also performed a set of experiments that show the proposed architecture for human-agent interaction increases the number and quality of user goals achieved

Towards the Prioritised Use of Transportation Infrastructures: The Case of Vehicle-Specific Dynamic Access Restrictions in City Centres

One of the main problems that local authorities of large cities have to face is the regulation of urban mobility. They need to provide the means to allow for the efficient movement of people and distribution of goods. However, the provisioning of transportation services needs to take into account general global objectives, like reducing emissions and having more healthy living environments, which may not always be aligned with individual interests. Urban mobility is usually provided through a transport infrastructure that includes all the elements that support mobility. On many occasions, the capacity of the elements of this infrastructure is lower than the actual demand and thus different transportation activities compete for their use. In this paper, we argue that scarce transport infrastructure elements should be assigned dynamically and in a prioritised manner to transport activities that have a higher utility from the point of view of society; for example, activities that produce less pollution and provide more value to society. In this paper, we define a general model for prioritizing the use of a particular type of transportation infrastructure element called time-unlimited elements, whose usage time is unknown a priori, and illustrate its dynamics through two use cases: vehicle-specific dynamic access restriction in city centres (i) based on the usage levels of available parking spaces and (ii) to assure sustained admissible air quality levels in the city centre. We carry out several experiments using the SUMO traffic simulation tool to evaluate our proposal