1,720,965 research outputs found
Effective Approaches for Handling Plan Constraints and Temporally Extended Goals in Automated Planning
No full textUna delle più importanti sfide dell'Intelligenza Artificiale (IA) è progettare agenti autonomi in grado di agire in ambienti complessi per raggiungere un obiettivo finale rispettando molteplici vincoli. Questa sfida è attualmente affrontata dalla Pianificazione Automatica, un campo dell'IA che si occupa del problema della sintesi di una sequenza di azioni, ovvero un piano, per raggiungere un insieme di obiettivi. Una parte rilevante della ricerca scientifica si concentra sui modelli di pianificazione classica, in cui gli obiettivi sono definiti come condizioni che devono essere soddisfatte nello stato finale raggiunto dall'esecuzione del piano. Tuttavia, questo approccio presenta alcune limitazioni significative; molti obiettivi degli agenti autonomi possono coinvolgere il mantenimento di una condizione di safety durante l'intera esecuzione del piano, reazioni a determinati input entro un periodo di tempo limitato, ed obiettivi aggiuntivi da raggiungere. Inoltre, diversi vincoli possono influenzare il comportamento dell'agente e la struttura dei piani desiderati.
Questa tesi affronta il problema della pianificazione con queste specifiche, ed esplora tre diverse modalità di formulazione di questi vincoli. In primo luogo, vengono considerati i vincoli sulla traiettoria degli stati definiti in PDDL3, uno dei linguaggi di pianificazione più diffusi. In secondo luogo, viene introdotto un nuovo formalismo per esprimere vincoli di traiettoria sulle azioni di un piano. Infine, vengono consideriati goal temporali espressi in Pure-Past Linear Temporal Logic.
Per ciascun formalismo, viene proposto uno schema di compilazione per tradurre problemi di pianificazione con queste specifiche in rappresentazioni equivalenti gestibili da pianificatori già esistenti. Tutte le compilazioni proposte sono polinomiali, corrette, complete e preservano la dimensione della soluzione.
Un’analisi sperimentale mostra che gli approcci proposti ottengono prestazioni migliori rispetto ad altre tecniche all'avanguardia nella maggior parte dei domini di pianificatione considerati.A significant challenge in Artificial Intelligence (AI) is to design autonomous systems that can act in complex environments to achieve a final objective while adhering to many constraints. This challenge is tackled by Automated Planning, which is a field of AI that deals with the problem of synthesizing a sequence of actions, i.e. a plan, to achieve a set of goals. A significant body of research focuses on classical planning models, where goals are defined as conditions that must hold in the final state reached by the plan execution. However, there are some major limitations to this approach; many goals of autonomous agents may involve the maintenance of a safety condition over the whole plan execution, reactions to certain inputs within a limited time frame, and intermediate objectives to achieve. Moreover, multiple constraints may dictate the agent's behavior and influence the structure of desired plans.
This thesis addresses the problem of planning under these specifications and explores three different ways of formulating these constraints. Firstly, we consider state trajectory constraints as defined in PDDL3, one of the most popular planning languages. Secondly, we introduce a new formalism for expressing trajectory constraints over actions rather than traversed states. Lastly, we consider temporally extended goals expressed in Pure-Past Linear Temporal Logic.
For each formalism, we propose a compilation schema to translate planning problems with these specifications into equivalent representations that can be handled by off-the-shelf classical planners. All proposed compilations are polynomial, sound, complete, and preserve the size of the solution.
Experimental analysis shows that the proposed approaches perform better than other state-of-the-art techniques in the majority of the considered benchmark domains
FOND Planning for Pure-Past Linear Temporal Logic Goals
Full text linkRecently, Pure-Past Temporal Logic (PPLTL) has proven highly effective in specifying temporally extended goals in deterministic planning domains. In this paper, we show its effectiveness also for fully observable nondeterministic (FOND) planning, both for strong and strong-cyclic plans. We present a notably simple encoding of FOND planning for PPLTL goals into standard FOND planning for final-state goals. The encoding only introduces few fluents (at most linear in the PPLTL goal) without adding any spurious action and allows planners to lazily build the relevant part of the deterministic automaton for the goal formula on-the-fly during the search. We formally prove its correctness, implement it in a tool called Plan4Past, and experimentally show its practical effectiveness
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Planning for Temporally Extended Goals in Pure-Past Linear Temporal Logic
Full text linkWe study classical planning for temporally extended goals expressed in Pure-Past Linear Temporal Logic (PPLTL).
PPLTL is as expressive as Linear-time Temporal Logic on finite traces (LTLf), but as shown in this paper, it is computationally much better behaved for planning.
Specifically, we show that planning for PPLTL goals can be encoded into classical planning with minimal overhead, introducing only a number of new fluents that is at most linear in the PPLTL goal and no spurious additional actions.
Based on these results, we implemented a system called Plan4Past, which can be used along with state-of-the-art classical planners, such as LAMA.
An empirical analysis demonstrates the practical effectiveness of Plan4Past, showing that a classical planner generally performs better with our compilation than with other existing compilations for LTLf goals over the considered benchmarks
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