A characterization of sequential rationalizability

A choice function is sequentially rationalizable if there is an ordered collection of asymmetric binary relations that identifies the selected alternative in every choice problem. We propose a property, F-consistency, and show that it characterizes the notion of sequential rationalizability. F-consistency is a testable property that highlights the behavioral aspects implicit in sequentially rationalizable choice. Further, our characterization result provides a novel tool with which to study how other behavioral concepts are related to sequential rationalizability, and establish a priori unexpected implications. In particular, we show that the concept of rationalizability by game trees, which, in principle, had little to do with sequential rationalizability, is a refinement of the latter. Every choice function that is rationalizable by a game tree is also sequentially rationalizable. Finally, we show that some prominent voting mechanisms are also sequentially rationalizable.Individual rationality, Rationalizability, Consistency, Bounded rationality, Behavioral economics, Voting

A Characterization of Single-Peaked Preferences

We identify in this paper two conditions that characterize the domain of single-peaked preferences on the line in the following sense: a preference profile satisfies these two properties if and only if there exists a linear order $L$ over the set of alternatives such that these preferences are single-peaked with respect L. The first property states that for any subset of alternatives the set of alternatives considered as the worst by all agents cannot contains more than 2 elements. The second property states that two agents cannot disagree on the relative ranking of two alternatives with respect to a third alternative but agree on the (relative) ranking of a fourth one.Single-peaked preferences, linear order.

A measure of rationality and welfare

There is evidence showing that individual behavior often deviates from the classical principle of maximization. This evidence raises at least two important questions: (i) how severe the deviations are and (ii) which method is the best for extracting relevant information from choice behavior for the purposes of welfare analysis. In this paper we address these two questions by identifying from a foundational analysis a new measure of the rationality of individuals that enables the analysis of individual welfare in potentially inconsistent subjects, all based on standard revealed preference data. We call such measure minimal index.Rationality; Individual Welfare; Revealed Preference.

Welfare of naive and sophisticated players in school choice

Two main school choice mechanisms have attracted the attention in the literature: Boston and deferred acceptance (DA). The question arises on the ex-ante welfare implications when the game is played by participants that vary in terms of their strategic sophistication. Abdulkadiroglu, Che and Yasuda (2011) have shown that the chances of naive participants getting into a good school are higher under the Boston mechanism than under DA, and some naive participants are actually better off. In this note we show that these results can be extended to show that, under the veil of ignorance, i.e. students not yet knowing their utility values, all naive students may prefer to adopt the Boston mechanism.School Choice; Naive Players; Welfare; Veil of Ignorance

A theory of reference-dependent behavior

Extensive field and experimental evidence in a variety of environments show that behavior depends on a reference point. This paper provides an axiomatic characterization of this dependence. We proceed by imposing gradually more structure on both choice correspondences and preference relations, requiring increasingly higher levels of rationality, and freeing the decision-maker from certain types of inconsistencies. The appropriate degree of behavioral structure will depend on the phenomenon that is to be modeled. Lastly, we provide two applications of our work: one to model the status-quo bias, and another to model addictive behavior.Individual rationality, reference-dependence, rationalization, path independence, status-quo bias, addiction, habit formation, LeeX

On the complexity of rationalizing behavior

We study the complexity of rationalizing choice behavior. We do so by analyzing two polar cases, and a number of intermediate ones. In our most structured case, that is where choice behavior is defined in universal choice domains and satisfies the "weak axiom of revealed preference," finding the complete preorder rationalizing choice behavior is a simple matter. In the polar case, where no restriction whatsoever is imposed, either on choice behavior or on choice domain, finding the complete preorders that rationalize behavior turns out to be intractable. We show that the task of finding the rationalizing complete preorders is equivalent to a graph problem. This allows the search for existing algorithms in the graph theory literature, for the rationalization of choice.Rationalization, Computational complexity, NP-complete, Arbitrary Choice Domains

Sincere Voting with Cardinal Preferences: Approval Voting

We discuss sincere voting when voters have cardinal preferences over alter- natives. We interpret sincerity as opposed to strategic voting, and thus define sincerity as the optimal behaviour when conditions to vote strategically vanish. When voting mechanisms allow for only one message type we show that this op- timal behaviour coincides with an intuitive and common definition of sincerity. For voting mechanisms allowing for multiple message types, such as approval vot- ing (AV), there exists no conclusive definition of sincerity in the literature. We show that for AV, voters' optimal strategy tends to one of the existent definitions of sincerity, consisting in voting for those alternatives that yield more than the average of cardinal utilities.sincere and strategic voting, approval voting

A foundation for strategic agenda voting

We offer complete characterizations of the equilibrium outcomes of two prominent agenda voting institutions that are widely used in the democratic world: the amendment, also known as the Anglo-American procedure, and the successive, or equivalently the Euro-Latin procedure. Our axiomatic approach provides a proper understanding of these voting institutions, and allows comparisons between them, and with other voting procedures.Strategic Voting, Agendas, Committees, Institutions, Axioms

Some Contributions to Interactive Machine Translation and to the Applications of Machine Translation for Historical Documents

[ES] Los documentos históricos son una parte importante de nuestra herencia cultural. Sin embargo, debido a la barrera idiomática inherente en el lenguaje humano y a las propiedades lingüísticas de estos documentos, su accesibilidad está principalmente restringida a los académicos. Por un lado, el lenguaje humano evoluciona con el paso del tiempo. Por otro lado, las convenciones ortográficas no se crearon hasta hace poco y, por tanto, la ortografía cambia según el período temporal y el autor. Por estas razones, el trabajo de los académicos es necesario para que los no expertos puedan obtener una comprensión básica de un documento determinado. En esta tesis abordamos dos tareas relacionadas con el procesamiento de documentos históricos. La primera tarea es la modernización del lenguaje que, a fin de hacer que los documentos históricos estén más accesibles para los no expertos, tiene como objetivo reescribir un documento utilizando la versión moderna del idioma original del documento. La segunda tarea es la normalización ortográfica. Las propiedades lingüísticas de los documentos históricos mencionadas con anterioridad suponen un desafío adicional para la aplicación efectiva del procesado del lenguaje natural en estos documentos. Por lo tanto, esta tarea tiene como objetivo adaptar la ortografía de un documento a los estándares modernos a fin de lograr una consistencia ortográfica. Ambas tareas las afrontamos desde una perspectiva de traducción automática, considerando el idioma original de un documento como el idioma fuente, y su homólogo moderno/normalizado como el idioma objetivo. Proponemos varios enfoques basados en la traducción automática estadística y neuronal, y llevamos a cabo una amplia experimentación que ratifica el potencial de nuestras contribuciones -en donde los enfoques estadísticos arrojan resultados iguales o mejores que los enfoques neuronales para la mayoría de los casos-. En el caso de la tarea de modernización del lenguaje, esta experimentación incluye una evaluación humana realizada con la ayuda de académicos y un estudio con usuarios que verifica que nuestras propuestas pueden ayudar a los no expertos a obtener una comprensión básica de un documento histórico sin la intervención de un académico. Como ocurre con cualquier problema de traducción automática, nuestras aplicaciones no están libres de errores. Por lo tanto, para obtener modernizaciones/normalizaciones perfectas, un académico debe supervisar y corregir los errores. Este es un procedimiento común en la industria de la traducción. La metodología de traducción automática interactiva tiene como objetivo reducir el esfuerzo necesario para obtener traducciones de alta calidad uniendo al agente humano y al sistema de traducción en un proceso de corrección cooperativo. Sin embargo,la mayoría de los protocolos interactivos siguen una estrategia de izquierda a derecha. En esta tesis desarrollamos un nuevo protocolo interactivo que rompe con esta barrera de izquierda a derecha. Hemos evaluado este nuevo protocolo en un entorno de traducción automática, obteniendo grandes reducciones del esfuerzo humano. Finalmente, dado que este marco interactivo es de aplicación general a cualquier problema de traducción, lo hemos aplicado -nuestro nuevo protocolo junto con uno de los protocolos clásicos de izquierda a derecha- a la modernización del lenguaje y a la normalización ortográfica. Al igual que en traducción automática, el marco interactivo logra disminuir el esfuerzo requerido para corregir los resultados de un sistema automático.[CA] Els documents històrics són una part important de la nostra herència cultural. No obstant això, degut a la barrera idiomàtica inherent en el llenguatge humà i a les propietats lingüístiques d'aquests documents, la seua accessibilitat està principalment restringida als acadèmics. D'una banda, el llenguatge humà evoluciona amb el pas del temps. D'altra banda, les convencions ortogràfiques no es van crear fins fa poc i, per tant, l'ortografia canvia segons el període temporal i l'autor. Per aquestes raons, el treball dels acadèmics és necessari perquè els no experts puguen obtindre una comprensió bàsica d'un document determinat. En aquesta tesi abordem dues tasques relacionades amb el processament de documents històrics. La primera tasca és la modernització del llenguatge que, a fi de fer que els documents històrics estiguen més accessibles per als no experts, té per objectiu reescriure un document utilitzant la versió moderna de l'idioma original del document. La segona tasca és la normalització ortogràfica. Les propietats lingüístiques dels documents històrics mencionades amb anterioritat suposen un desafiament addicional per a l'aplicació efectiva del processat del llenguatge natural en aquests documents. Per tant, aquesta tasca té per objectiu adaptar l'ortografia d'un document als estàndards moderns a fi d'aconseguir una consistència ortogràfica. Dues tasques les afrontem des d'una perspectiva de traducció automàtica, considerant l'idioma original d'un document com a l'idioma font, i el seu homòleg modern/normalitzat com a l'idioma objectiu. Proposem diversos enfocaments basats en la traducció automàtica estadística i neuronal, i portem a terme una àmplia experimentació que ratifica el potencial de les nostres contribucions -on els enfocaments estadístics obtenen resultats iguals o millors que els enfocaments neuronals per a la majoria dels casos-. En el cas de la tasca de modernització del llenguatge, aquesta experimentació inclou una avaluació humana realitzada amb l'ajuda d'acadèmics i un estudi amb usuaris que verifica que les nostres propostes poden ajudar als no experts a obtindre una comprensió bàsica d'un document històric sense la intervenció d'un acadèmic. Com ocurreix amb qualsevol problema de traducció automàtica, les nostres aplicacions no estan lliures d'errades. Per tant, per obtindre modernitzacions/normalitzacions perfectes, un acadèmic ha de supervisar i corregir les errades. Aquest és un procediment comú en la indústria de la traducció. La metodologia de traducció automàtica interactiva té per objectiu reduir l'esforç necessari per obtindre traduccions d'alta qualitat unint a l'agent humà i al sistema de traducció en un procés de correcció cooperatiu. Tot i això, la majoria dels protocols interactius segueixen una estratègia d'esquerra a dreta. En aquesta tesi desenvolupem un nou protocol interactiu que trenca amb aquesta barrera d'esquerra a dreta. Hem avaluat aquest nou protocol en un entorn de traducció automàtica, obtenint grans reduccions de l'esforç humà. Finalment, atès que aquest marc interactiu és d'aplicació general a qualsevol problema de traducció, l'hem aplicat -el nostre nou protocol junt amb un dels protocols clàssics d'esquerra a dreta- a la modernització del llenguatge i a la normalitzaciò ortogràfica. De la mateixa manera que en traducció automàtica, el marc interactiu aconsegueix disminuir l'esforç requerit per corregir els resultats d'un sistema automàtic.[EN] Historical documents are an important part of our cultural heritage. However,due to the language barrier inherent in human language and the linguistic properties of these documents, their accessibility is mostly limited to scholars. On the one hand, human language evolves with the passage of time. On the other hand, spelling conventions were not created until recently and, thus, orthography changes depending on the time period and author. For these reasons, the work of scholars is needed for non-experts to gain a basic understanding of a given document. In this thesis, we tackle two tasks related with the processing of historical documents. The first task is language modernization which, in order to make historical documents more accessible to non-experts, aims to rewrite a document using the modern version of the document's original language. The second task is spelling normalization. The aforementioned linguistic properties of historical documents suppose an additional challenge for the effective natural language processing of these documents. Thus, this task aims to adapt a document's spelling to modern standards in order to achieve an orthography consistency. We affront both task from a machine translation perspective, considering a document's original language as the source language, and its modern/normalized counterpart as the target language. We propose several approaches based on statistical and neural machine translation, and carry out a wide experimentation that shows the potential of our contributions¿with the statistical approaches yielding equal or better results than the neural approaches in most of the cases. For the language modernization task, this experimentation includes a human evaluation conducted with the help of scholars and a user study that verifies that our proposals are able to help non-experts to gain a basic understanding of a historical document without the intervention of a scholar. As with any machine translation problem, our applications are not error-free. Thus, to obtain perfect modernizations/normalizations, a scholar needs to supervise and correct the errors. This is a common procedure in the translation industry. The interactive machine translation framework aims to reduce the effort needed for obtaining high quality translations by embedding the human agent and the translation system into a cooperative correction process. However, most interactive protocols follow a left-to-right strategy. In this thesis, we developed a new interactive protocol that breaks this left-to-right barrier. We evaluated this new protocol in a machine translation environment, obtaining large reductions of the human effort. Finally, since this interactive framework is of general application to any translation problem, we applied it¿our new protocol together with one of the classic left-to-right protocols¿to language modernization and spelling normalization. As with machine translation, the interactive framework diminished the effort required for correcting the outputs of an automatic system.The research leading to this thesis has been partially funded by Ministerio de Economía y Competitividad (MINECO) under projects SmartWays (grant agreement RTC-2014-1466-4), CoMUN-HaT (grant agreement TIN2015-70924-C2-1-R) and MISMISFAKEnHATE (grant agreement PGC2018-096212-B-C31); Generalitat Valenciana under projects ALMAMATER (grant agreement PROMETEOII/2014/030) and DeepPattern (grant agreement PROMETEO/2019/121); the European Union through Programa Operativo del Fondo Europeo de Desarrollo Regional (FEDER) from Comunitat Valenciana (2014–2020) under project Sistemas de frabricación inteligentes para la indústria 4.0 (grant agreement ID-IFEDER/2018/025); and the PRHLT research center under the research line Machine Learning Applications.Domingo Ballester, M. (2022). Some Contributions to Interactive Machine Translation and to the Applications of Machine Translation for Historical Documents [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/181231TESI

Sincerity in Simple and Complex Voting Mechanisms

We discuss sincere voting when voters have cardinal preferences over alternatives. We interpret sincerity as opposed to strategic voting, and thus define sincerity as the optimal behavior when conditions to vote strategically diminish. When voting mechanisms allow for only one message type (simple voting mechanisms) we show that eliminating some conditions for strategic voting, individuals' optimal behavior coincides with an intuitive and common definition of sincerity. In order to obtain a precise definition of sincerity in voting mechanisms allowing for multiple message types (complex voting mechanisms) further restrictions on strategic voting are required. We illustrate our methodological approach using approval voting (AV) as a prime example of complex voting mechanisms for which no conclusive definition of sincerity exists in the literature.sincere and strategic voting, cardinal utility, approval voting