iCORPP: Interleaved Commonsense Reasoning and Probabilistic Planning on Robots

Robot sequential decision-making in the real world is a challenge because it requires the robots to simultaneously reason about the current world state and dynamics, while planning actions to accomplish complex tasks. On the one hand, declarative languages and reasoning algorithms well support representing and reasoning with commonsense knowledge. But these algorithms are not good at planning actions toward maximizing cumulative reward over a long, unspecified horizon. On the other hand, probabilistic planning frameworks, such as Markov decision processes (MDPs) and partially observable MDPs (POMDPs), well support planning to achieve long-term goals under uncertainty. But they are ill-equipped to represent or reason about knowledge that is not directly related to actions. In this article, we present a novel algorithm, called iCORPP, to simultaneously estimate the current world state, reason about world dynamics, and construct task-oriented controllers. In this process, robot decision-making problems are decomposed into two interdependent (smaller) subproblems that focus on reasoning to "understand the world" and planning to "achieve the goal" respectively. Contextual knowledge is represented in the reasoning component, which makes the planning component epistemic and enables active information gathering. The developed algorithm has been implemented and evaluated both in simulation and on real robots using everyday service tasks, such as indoor navigation, dialog management, and object delivery. Results show significant improvements in scalability, efficiency, and adaptiveness, compared to competitive baselines including handcrafted action policies

An Approach for Intention-Driven, Dialogue-Based Web Search

Web search engines facilitate the achievement of Web-mediated tasks, including information retrieval, Web page navigation, and online transactions. These tasks often involve goals that pertain to multiple topics, or domains. Current search engines are not suitable for satisfying complex, multi-domain needs due to their lack of interactivity and knowledge. This thesis presents a novel intention-driven, dialogue-based Web search approach that uncovers and combines users\u27 multi-domain goals to provide helpful virtual assistance. The intention discovery procedure uses a hierarchy of Partially Observable Markov Decision Process-based dialogue managers and a backing knowledge base to systematically explore the dialogue\u27s information space, probabilistically refining the perception of user goals. The search approach has been implemented in IDS, a search engine for online gift shopping. A usability study comparing IDS-based searching with Google-based searching found that the IDS-based approach takes significantly less time and effort, and results in higher user confidence in the retrieved results

Apprentissage par renforcement pour la généralisation des approches automatiques dans la conception des systèmes de dialogue oral

Les systèmes de dialogue homme machine actuellement utilisés dans l industrie sont fortement limités par une forme de communication très rigide imposant à l utilisateur de suivre la logique du concepteur du système. Cette limitation est en partie due à leur représentation de l état de dialogue sous la forme de formulaires préétablis.Pour répondre à cette difficulté, nous proposons d utiliser une représentation sémantique à structure plus riche et flexible visant à permettre à l utilisateur de formuler librement sa demande.Une deuxième difficulté qui handicape grandement les systèmes de dialogue est le fort taux d erreur du système de reconnaissance vocale. Afin de traiter ces erreurs de manière quantitative, la volonté de réaliser une planification de stratégie de dialogue en milieu incertain a conduit à utiliser des méthodes d apprentissage par renforcement telles que les processus de décision de Markov partiellement observables (POMDP). Mais un inconvénient du paradigme POMDP est sa trop grande complexité algorithmique. Certaines propositions récentes permettent de réduire la complexité du modèle. Mais elles utilisent une représentation en formulaire et ne peuvent être appliqués directement à la représentation sémantique riche que nous proposons d utiliser.Afin d appliquer le modèle POMDP dans un système dont le modèle sémantique est complexe, nous proposons une nouvelle façon de contrôler sa complexité en introduisant un nouveau paradigme : le POMDP résumé à double suivi de la croyance. Dans notre proposition, le POMDP maitre, complexe, est transformé en un POMDP résumé, plus simple. Un premier suivi de croyance (belief update) est réalisé dans l espace maitre (en intégrant des observations probabilistes sous forme de listes nbest). Et un second suivi de croyance est réalisé dans l espace résumé, les stratégies obtenues sont ainsi optimisées sur un véritable POMDP.Nous proposons deux méthodes pour définir la projection du POMDP maitre en un POMDP résumé : par des règles manuelles et par regroupement automatique par k plus proches voisins. Pour cette dernière, nous proposons d utiliser la distance d édition entre graphes, que nous généralisons pour obtenir une distance entre listes nbest.En outre, le couplage entre un système résumé, reposant sur un modèle statistique par POMDP, et un système expert, reposant sur des règles ad hoc, fournit un meilleur contrôle sur la stratégie finale. Ce manque de contrôle est en effet une des faiblesses empêchant l adoption des POMDP pour le dialogue dans l industrie.Dans le domaine du renseignement d informations touristiques et de la réservation de chambres d hôtel, les résultats sur des dialogues simulés montrent l efficacité de l approche par renforcement associée à un système de règles pour s adapter à un environnement bruité. Les tests réels sur des utilisateurs humains montrent qu un système optimisé par renforcement obtient cependant de meilleures performances sur le critère pour lequel il a été optimisé.Dialog managers (DM) in spoken dialogue systems make decisions in highly uncertain conditions, due to errors from the speech recognition and spoken language understanding (SLU) modules. In this work a framework to interface efficient probabilistic modeling for both the SLU and the DM modules is described and investigated. Thorough representation of the user semantics is inferred by the SLU in the form of a graph of frames and, complemented with some contextual information, is mapped to a summary space in which a stochastic POMDP dialogue manager can perform planning of actions taking into account the uncertainty on the current dialogue state. Tractability is ensured by the use of an intermediate summary space. Also to reduce the development cost of SDS an approach based on clustering is proposed to automatically derive the master-summary mapping function. A implementation is presented in the Media corpus domain (touristic information and hotel booking) and tested with a simulated user.AVIGNON-Bib. numérique (840079901) / SudocSudocFranceF

Evolutionary Reinforcement Learning of Spoken Dialogue Strategies

Institute for Communicating and Collaborative SystemsFrom a system developer's perspective, designing a spoken dialogue system can be a time-consuming and difficult process. A developer may spend a lot of time anticipating how a potential user might interact with the system and then deciding on the most appropriate system response. These decisions are encoded in a dialogue strategy, essentially a mapping between anticipated user inputs and appropriate system outputs. To reduce the time and effort associated with developing a dialogue strategy, recent work has concentrated on modelling the development of a dialogue strategy as a sequential decision problem. Using this model, reinforcement learning algorithms have been employed to generate dialogue strategies automatically. These algorithms learn strategies by interacting with simulated users. Some progress has been made with this method but a number of important challenges remain. For instance, relatively little success has been achieved with the large state representations that are typical of real-life systems. Another crucial issue is the time and effort associated with the creation of simulated users. In this thesis, I propose an alternative to existing reinforcement learning methods of dialogue strategy development. More specifically, I explore how XCS, an evolutionary reinforcement learning algorithm, can be used to find dialogue strategies that cover large state spaces. Furthermore, I suggest that hand-coded simulated users are sufficient for the learning of useful dialogue strategies. I argue that the use of evolutionary reinforcement learning and hand-coded simulated users is an effective approach to the rapid development of spoken dialogue strategies. Finally, I substantiate this claim by evaluating a learned strategy with real users. Both the learned strategy and a state-of-the-art hand-coded strategy were integrated into an end-to-end spoken dialogue system. The dialogue system allowed real users to make flight enquiries using a live database for an Edinburgh-based airline. The performance of the learned and hand-coded strategies were compared. The evaluation results show that the learned strategy performs as well as the hand-coded one (81% and 77% task completion respectively) but takes much less time to design (two days instead of two weeks). Moreover, the learned strategy compares favourably with previous user evaluations of learned strategies

User Simulation for Spoken Dialog System Development

A user simulation is a computer program which simulates human user behaviors. Recently, user simulations have been widely used in two spoken dialog system development tasks. One is to generate large simulated corpora for applying machine learning to learn new dialog strategies, and the other is to replace human users to test dialog system performance. Although previous studies have shown successful examples of applying user simulations in both tasks, it is not clear what type of user simulation is most appropriate for a specific task because few studies compare different user simulations in the same experimental setting. In this research, we investigate how to construct user simulations in a specific task for spoken dialog system development. Since most current user simulations generate user actions based on probabilistic models, we identify two main factors in constructing such user simulations: the choice of user simulation model and the approach to set up user action probabilities. We build different user simulation models which differ in their efforts in simulating realistic user behaviors and exploring more user actions. We also investigate different manual and trained approaches to set up user action probabilities. We introduce both task-dependent and task-independent measures to compare these simulations. We show that a simulated user which mimics realistic user behaviors is not always necessary for the dialog strategy learning task. For the dialog system testing task, a user simulation which simulates user behaviors in a statistical way can generate both objective and subjective measures of dialog system performance similar to human users. Our research examines the strengths and weaknesses of user simulations in spoken dialog system development. Although our results are constrained to our task domain and the resources available, we provide a general framework for comparing user simulations in a task-dependent context. In addition, we summarize and validate a set of evaluation measures that can be used in comparing different simulated users as well as simulated versus human users

Designing coherent and engaging open-domain conversational AI systems

Designing conversational AI systems able to engage in open-domain ‘social’ conversation is extremely challenging and a frontier of current research. Such systems are required to have extensive awareness of the dialogue context and world knowledge, the user intents and interests, requiring more complicated language understanding, dialogue management, and state and topic tracking mechanisms compared to traditional task-oriented dialogue systems. Given the wide coverage of topics in open-domain dialogue, the conversation can span multiple turns where a number of complex linguistic phenomena (e.g. ellipsis and anaphora) are present and should be resolved for the system to be contextually aware. Such systems also need to be engaging, keeping the users’ interest over long conversations. These are only some of the challenges that open-domain dialogue systems face. Therefore this thesis focuses on designing dialogue systems able to hold extensive open-domain conversations in a coherent, engaging, and appropriate manner over multiple turns. First, different types of dialogue systems architecture and design decisions are discussed for social open-domain conversations, along with relevant evaluation metrics. A modular architecture for ensemble-based conversational systems is presented, called Alana, a finalist in the Amazon Alexa Prize Challenge in 2017 and 2018, able to tackle many of the challenges for open-domain social conversation. The system combines different features such as topic tracking, contextual Natural Language understanding, entity linking, user modelling, information retrieval, and response ranking, using a rich representation of dialogue state. The thesis next analyses the performance of the 2017 system and describes the upgrades developed for the 2018 system. This leads to an analysis and comparison of the real-user data collected in both years with different system configurations, allowing assessment of the impact of different design decisions and modules. Finally, Alana was integrated into an embodied robotic platform and enhanced with the ability to also perform tasks. This system was deployed and evaluated in a shopping mall in Finland. Further analysis of the added embodiment is presented and discussed, as well as the challenges of translating open-domain dialogue systems into other languages. Data analysis of the collected real-user data shows the importance of a variety of features developed and decisions made in the design of the Alana system

The significance of silence. Long gaps attenuate the preference for ‘yes’ responses in conversation.

In conversation, negative responses to invitations, requests, offers and the like more often occur with a delay – conversation analysts talk of them as dispreferred. Here we examine the contrastive cognitive load ‘yes’ and ‘no’ responses make, either when given relatively fast (300 ms) or delayed (1000 ms). Participants heard minidialogues, with turns extracted from a spoken corpus, while having their EEG recorded. We find that a fast ‘no’ evokes an N400-effect relative to a fast ‘yes’, however this contrast is not present for delayed responses. This shows that an immediate response is expected to be positive – but this expectation disappears as the response time lengthens because now in ordinary conversation the probability of a ‘no’ has increased. Additionally, however, 'No' responses elicit a late frontal positivity both when they are fast and when they are delayed. Thus, regardless of the latency of response, a ‘no’ response is associated with a late positivity, since a negative response is always dispreferred and may require an account. Together these results show that negative responses to social actions exact a higher cognitive load, but especially when least expected, as an immediate response

Social talk capabilities for dialogue systems

Small talk capabilities are an important but very challenging extension to dialogue systems. Small talk (or social talk) refers to a kind of conversation, which does not focus on the exchange of information, but on the negotiation of social roles and situations. The goal of this thesis is to provide knowledge, processes and structures that can be used by dialogue systems to satisfactorily participate in social conversations. For this purpose the thesis presents research in the areas of natural-language understanding, dialogue management and error handling. Nine new models of social talk based on a data analysis of small talk conversations are described. The functionally-motivated and content-abstract models can be used for small talk conversations on various topics. The basic elements of the models consist of dialogue acts for social talk newly developed on basis of social science theory. The thesis also presents some conversation strategies for the treatment of so-called out-of-domain (OoD) utterances that can be used to avoid errors in the input understanding of dialogue systems. Additionally, the thesis describes a new extension to dialogue management that flexibly manages interwoven dialogue threads. The small talk models as well as the strategies for handling OoD utterances are encoded as computational dialogue threads