New axiomatizations of the Shapley interaction index for bi-capacities

International audienceBi-capacities are a natural generalization of capacities (or fuzzy measures) in a context of decision making where underlying scales are bipolar. They are able to capture a wide variety of decision behaviours. After a short presentation of the basis structure, we introduce the Shapley value and the interaction index for capacities. Afterwards, the case of bi-capacities is studied with new axiomatizations of the interaction index

A decade of application of the Choquet and Sugeno integrals in multi-criteria decision aid

The main advances regarding the use of the Choquet and Sugeno integrals in multi-criteria decision aid over the last decade are reviewed. They concern mainly a bipolar extension of both the Choquet integral and the Sugeno integral, interesting particular submodels, new learning techniques, a better interpretation of the models and a better use of the Choquet integral in multi-criteria decision aid. Parallel to these theoretical works, the Choquet integral has been applied to many new fields, and several softwares and libraries dedicated to this model have been developed.Choquet integral, Sugeno integral, capacity, bipolarity, preferences

Az erős,a gyenge, meg a ravasz: Hatalom és stratégiai viselkedés szavazási játékokban = The Strong, the Weak and the Cunning: Power and Strategy in Voting Games

Kutatási eredményeink három téma köré csoportosíthatók. Ezek közül az első a stratégiai megfontolások vizsgálata. Megmutatjuk, hogy a szavazók növelhetik befolyásukat, ha veszekednek más szavazókkal és a stratégiai hatalmi indexek jól definiáltak a játékok bizonyos osztályaira. Egy másik vonal a kooperatív játékok olyan kulcsfontosságú tulajdonságait vizsgálja, mint a konvexitás, vagy az egzaktság. Bizonyos esetekben a nyerő koalíciók halmaza külső okok miatt korlátozott: erre a leggyakoribb példa, mikor egy hálózaton elhelyezkedő csúcsok helyzeti befolyását vizsgáljuk. A csúcsok csak az őket összekötő élek mentén kommunikálhatnak és csak szomszédaikkal. Több érték és index is kiterjesztésre, illetve bevezetésre kerül ilyen hálózati játékokra, illetve az értékekhez axiomatikus karakterizációt adunk. Végül a hatalmi indexeket olyan játékokra is kiterjesztjük, ahol egyes szavazók hiányozhatnak. A nem stratégiai hiányzást vizsgáljuk és a Shapley értéket teljesen karakterizáljuk az általánosított súlyozott szavazási játékok osztályán. Modellünket különböző parlamentekre alkalmazzuk, illetve az elméleti módszerek több egyéb alkalmazását is vizsgáltuk, úgymint a Lisszaboni Szerződés hatását a Miniszterek Tanácsában folyó súlyozott szavazás hatalmi viszonyaira. | The results of the project centre around three themes. The first is strategic considerations. We have shown that voters are able to increase their power by strategic quarrelling and the strategic power indices are well defined for certain classes of games. Additional papers provide tests on key properties, such as convexity and exactness of cooperative games. In some situations the set of feasible (winning) coalitions is restricted exogenously. The most common example is to study positional power over a network where the voters are located at the nodes and can only communicate with their neighbours. Several values and indices are introduced and characterised for games over networks. At last we generalised power indices to weighted voting games where representatives may be absent. We study non-strategic absenteeism and characterise the Shapley value for the class of generalised weighted voting games. We have also studied applications studying the effect of absent voters in various national parliaments or the effect of the Lisbon Treaty of the European Union to the power balance in the Council of Ministers

Axiomatizations of the Choquet integral on general decision spaces

PhDWe propose an axiomatization of the Choquet integral model for the general case of a heterogeneous product set X = X1 Xn. Previous characterizations of the Choquet integral have been given for the particular cases X = Y n and X = Rn. However, this makes the results inapplicable to problems in many fields of decision theory, such as multicriteria decision analysis (MCDA), state-dependent utility (SD-DUU), and social choice. For example, in multicriteria decision analysis the elements of X are interpreted as alternatives, characterized by criteria taking values from the sets Xi. Obviously, the identicalness or even commensurateness of criteria cannot be assumed a priori. Despite this theoretical gap, the Choquet integral model is quite popular in the MCDA community and is widely used in applied and theoretical works. In fact, the absence of a sufficiently general axiomatic treatment of the Choquet integral has been recognized several times in the decision-theoretic literature. In our work we aim to provide missing results { we construct the axiomatization based on a novel axiomatic system and study its uniqueness properties. Also, we extend our construction to various particular cases of the Choquet integral and analyse the constraints of the earlier characterizations. Finally, we discuss in detail the implications of our results for the applications of the Choquet integral as a model of decision making

Governance of Clubs and Firms with Cultural Dimensions

The neoclassical way to cope with firms providing services, or with clubs procuring services, is restricted by the lack of institutional features. An institutional approach is introduced that requires a cooperative governance to realize the potential value-production by firms, or to realize the potential user-value by clubs. For each, a distinctive governance system is introduced. The firm requires an implementation governance to activate the value-production capacities of its service providers. It is empowered top-down by the unique top- position of the organization. The club, on the other hand, requires a representation governance to aggregate the user-values of its members for some common service and to order this service. It is empowered bottom-up by the service-users, i.e., the members of the club using that common service. Institutional characteristics are also re ected in the distribution functions that are used inrewarding positions in firms and clubs. Some cultural dimensions are expressed in these distribution functions. That allows us to relate characteristics of governance systems to society's cultural dimensions.

Potential Games and Interactive Decisions with Multiple Criteria.

Abstract: Game theory is a mathematical theory for analyzing strategic interaction between decision makers. This thesis covers two game-theoretic topics. The first part of this thesis deals with potential games: noncooperative games in which the information about the goals of the separate players that is required to determine equilibria, can be aggregated into a single function. The structure of different types of potential games is investigated. Congestion problems and the financing of public goods through voluntary contributions are studied in this framework. The second part of the thesis abandons the common assumption that each player is guided by a single goal. It takes into account players who are guided by several, possibly conflicting, objective functions.

A POWER INDEX BASED FRAMEWORKFOR FEATURE SELECTION PROBLEMS

One of the most challenging tasks in the Machine Learning context is the feature selection. It consists in selecting the best set of features to use in the training and prediction processes. There are several benefits from pruning the set of actually operational features: the consequent reduction of the computation time, often a better quality of the prediction, the possibility to use less data to create a good predictor. In its most common form, the problem is called single-view feature selection problem, to distinguish it from the feature selection task in Multi-view learning. In the latter, each view corresponds to a set of features and one would like to enact feature selection on each view, subject to some global constraints. A related problem in the context of Multi-View Learning, is Feature Partitioning: it consists in splitting the set of features of a single large view into two or more views so that it becomes possible to create a good predictor based on each view. In this case, the best features must be distributed between the views, each view should contain synergistic features, while features that interfere disruptively must be placed in different views. In the semi-supervised multi-view task known as Co-training, one requires also that each predictor trained on an individual view is able to teach something to the other views: in classification tasks for instance, one view should learn to classify unlabelled examples based on the guess provided by the other views. There are several ways to address these problems. A set of techniques is inspired by Coalitional Game Theory. Such theory defines several useful concepts, among which two are of high practical importance: the concept of power index and the concept of interaction index. When used in the context of feature selection, they take the following meaning: the power index is a (context-dependent) synthesis measure of the prediction\u2019s capability of a feature, the interaction index is a (context-dependent) synthesis measure of the interaction (constructive/disruptive interference) between two features: it can be used to quantify how the collaboration between two features enhances their prediction capabilities. An important point is that the powerindex of a feature is different from the predicting power of the feature in isolation: it takes into account, by a suitable averaging, the context, i.e. the fact that the feature is acting, together with other features, to train a model. Similarly, the interaction index between two features takes into account the context, by suitably averaging the interaction with all the other features. In this work we address both the single-view and the multi-view problems as follows. The single-view feature selection problem, is formalized as the problem of maximization of a pseudo-boolean function, i.e. a real valued set function (that maps sets of features into a performance metric). Since one has to enact a search over (a considerable portion of) the Boolean lattice (without any special guarantees, except, perhaps, positivity) the problem is in general NP-hard. We address the problem producing candidate maximum coalitions through the selection of the subset of features characterized by the highest power indices and using the coalition to approximate the actual maximum. Although the exact computation of the power indices is an exponential task, the estimates of the power indices for the purposes of the present problem can be achieved in polynomial time. The multi-view feature selection problem is formalized as the generalization of the above set-up to the case of multi-variable pseudo-boolean functions. The multi-view splitting problem is formalized instead as the problem of maximization of a real function defined over the partition lattice. Also this problem is typically NP-hard. However, candidate solutions can be found by suitably partitioning the top power-index features and keeping in different views the pairs of features that are less interactive or negatively interactive. The sum of the power indices of the participating features can be used to approximate the prediction capability of the view (i.e. they can be used as a proxy for the predicting power). The sum of the feature pair interactivity across views can be used as proxy for the orthogonality of the views. Also the capability of a view to pass information (to teach) to other views, within a co-training procedure can benefit from the use of power indices based on a suitable definition of information transfer (a set of features { a coalition { classifies examples that are subsequently used in the training of a second set of features). As to the feature selection task, not only we demonstrate the use of state of the art power index concepts (e.g. Shapley Value and Banzhaf along the 2lines described above Value), but we define new power indices, within the more general class of probabilistic power indices, that contains the Shapley and the Banzhaf Values as special cases. Since the number of features to select is often a predefined parameter of the problem, we also introduce some novel power indices, namely k-Power Index (and its specializations k-Shapley Value, k-Banzhaf Value): they help selecting the features in a more efficient way. For the feature partitioning, we use the more general class of probabilistic interaction indices that contains the Shapley and Banzhaf Interaction Indices as members. We also address the problem of evaluating the teaching ability of a view, introducing a suitable teaching capability index. The last contribution of the present work consists in comparing the Game Theory approach to the classical Greedy Forward Selection approach for feature selection. In the latter the candidate is obtained by aggregating one feature at time to the current maximal coalition, by choosing always the feature with the maximal marginal contribution. In this case we show that in typical cases the two methods are complementary, and that when used in conjunction they reduce one another error in the estimate of the maximum value. Moreover, the approach based on game theory has two advantages: it samples the space of all possible features\u2019 subsets, while the greedy algorithm scans a selected subspace excluding totally the rest of it, and it is able, for each feature, to assign a score that describes a context-aware measure of importance in the prediction process

Estructura Combinatoria de Politopos asociados a Medidas Difusas

Tesis inédita de la Universidad Complutense de Madrid, Facultad de Ciencias Matemáticas, leída el 23-11-2020This PhD thesis is devoted to the study of geometric and combinatorial aspects of polytopes associated to fuzzy measures. Fuzzy measures are an essential tool, since they generalize the concept of probability. This greater generality allows applications to be developed in various elds, from the Decision Theory to the Game Theory. The set formed by all fuzzy measures on a referential set is a polytope. In the same way, many of the most relevant subfamilies of fuzzy measures are also polytopes. Studying the combinatorial structure of these polytopes arises as a natural problem that allows us to better understand the properties of the associated fuzzy measures. Knowing the combinatorial structure of these polytopes helps us to develop algorithms to generate points uniformly at random inside these polytopes. Generating points uniformly inside a polytope is a complex problem from both a theoretical and a computational point of view. Having algorithms that allow us to sample uniformly in polytopes associated to fuzzy measures allows us to solve many problems, among them the identi cation problem, i.e. estimate the fuzzy measure that underlies an observed data set...La presente tesis doctoral esta dedicada al estudio de distintas propiedades geometricas y combinatorias de politopos de medidas difusas. Las medidas difusas son una herramienta esencial puesto que generalizan el concepto de probabilidad. Esta mayor generalidad permite desarrollar aplicaciones en diversos campos, desde la Teoría de la Decision a laTeoría de Juegos. El conjunto formado por todas las medidas difusas sobre un referencial tiene estructura de politopo. De la misma forma, la mayora de las subfamilias mas relevantes de medidas difusas son tambien politopos. Estudiar la estructura combinatoria de estos politopos surge como un problema natural que nos permite comprender mejor las propiedades delas medidas difusas asociadas. Conocer la estructura combinatoria de estos politopos tambien nos ayuda a desarrollar algoritmos para generar aleatoria y uniformemente puntos dentro de estos politopos. Generar puntos de forma uniforme dentro de un politopo es un problema complejo desde el punto de vista tanto teorico como computacional. Disponer de algoritmos que nos permitan generar uniformemente en politopos asociados a medidas difusas nos permite resolver muchos problemas, entre ellos el problema de identificacion que trata de estimarla medida difusa que subyace a un conjunto de datos observado...Fac. de Ciencias MatemáticasTRUEunpu