This paper presents a model-driven approach to detect image line segments. The approach incrementally detects segments on the gradient image using a linear Kalman filter that estimates the supporting line parameters and their associated variances. The algorithm is fast and robust with respect to image noise and illumination variations, it allows the detection of longer line segments than data-driven approaches, and does not require any tedious parameters tuning. An extension of the algorithm that exploits a pyramidal approach to enhance the quality of results is proposed. Results with varying scene illumination and comparisons to classic existing approaches are presented.

Real life optimization often concerns difficult objective functions, in two aspects, namely that gradients are unavailable, and that evaluation of the objective function takes a long time. Such problems are often attacked with model building algorithms, where an approximation of the function is constructed and solved, in order to find a new promising point to evaluate. We study several ways of saving time by using parallel calculations in the context of model building algorithms, which is not trivial, since such algorithms are inherently sequential. We present a number of ideas that has been implemented and tested on a large number of known test functions, and a few new ones. The computational results reveal that some ideas are quite promising.

Welcome to SweCog 2018 in Linköping!This booklet contains the program and short papers for oral and poster presentations at SweCog 2018, this year’s edition of the annual conference of the Swedish Cognitive Science Society. Following the SweCog tradition and its aim to support networking among researchers in cognitive science and related areas, contributions cover a wide spectrum of research.A trend in recent years, also reflected in this year’s conference program, is an increasing number of contributions that deal with different types of autonomous technologies, such as social robots, virtual agents or automated vehicles, and in particular people’s interaction with such systems. This clearly is a growing research area of high societal relevance, where cognitive science - with its interdisciplinary and human-centered approach - can make significant contributions.We look forward to two exciting days in Linköping, and we thank the many people who have contributed to the organization of this year’s SweCog conference, in particular of course all authors and reviewers! The organization of SweCog 2018 has been supported by the Faculty of Arts and Sciences, the Department of Culture Communication (IKK), and the Department of Computer Information Science (IDA) at Linköpping University, as well as Cambio Healthcare Systems and Visual Sweden.Tom Ziemke, Mattias Arvola, Nils Dahlbäc and Erik Billing

Guarding the perimeter of an area in order to detect potential intruders is an important task in a variety of security-related applications. This task can in many circumstances be performed by a set of camera-equipped unmanned aerial vehicles (UAVs). Such UAVs will occasionally require refueling or recharging, in which case they must temporarily be replaced by other UAVs in order to maintain complete surveillance of the perimeter. In this paper we consider the problem of scheduling such replacements. We present optimal replacement strategies and justify their optimality.

We consider the directed Steiner tree problem (DSTP) with a constraint on the total number of arcs (hops) in the tree. This problem is known to be NP-hard, and therefore, only heuristics can be applied in the case of its large-scale instances. For the hop-constrained DSTP, we propose local search strategies aimed at improving any heuristically produced initial Steiner tree. They are based on solving a sequence of hop-constrained shortest path problems for which we have recently developed ecient label correcting algorithms. The presented approach is applied to nding suitable 3D locations where unmanned aerial vehicles (UAVs) can be placed to relay information gathered in multi-target monitoring and surveillance. The eciency of our algorithms is illustrated by results of numerical experiments involving problem instances with up to 40 000 nodes and up to 20 million arcs.

Nicht nur in der Logistik und in der Produktion setzt es sich immer mehr durch, die Steuerung und Überwachung von Aufgaben zu verteilen. Für eine solche Vorgehens- weise sind sogenannte Multi-Agenten-Systeme (MAS) geeignet, bei denen mehrere ei- genständige Systeme miteinander kommunizieren, sich koordinieren und kooperieren. Eine spezielle Form solcher MAS sind Multi-Roboter-Systeme.

In der Logisitk, in der Produktion und und in anderen Bereichen setzt es sich immer mehr durch, zentrale Instanzen zu vermeiden und die Steuerung und Überwachung von Aufgaben zu verteilen. Für eine solche Vorgehensweise sind so genannte Multi-Agenten-Systeme (MAS) ideal geeignet, bei denen mehrere eigenständige Systeme miteinander kommunizieren, sich koordinieren und kooperieren. Eine spezielle Form solcher MAS sind Multi-Roboter-Systeme, bei denen die einzelnen Agenten sich selbständig bewegende physikalische Einheiten sind, wie z.B. bei einer Gruppe von Reinigungsrobotern, einem Roboterfußballteam oder im Logistiksystem KARIS.

Open peer review has been proposed for a number of reasons, in particular, for increasing the transparency of the article selection process for a journal, and for obtaining a broader basis for feedback to the authors and for the acceptance decision. The review discussion may also in itself have a value for the research community. These goals rely on the existence of a lively review discussion, but several experiments with open-process peer review in recent years have encountered the problem of faltering review discussions. The present article addresses the question of how lively review discussion may be fostered by relating the experience of the journal Electronic Transactions on Artificial Intelligence (ETAI) which was an early experiment with open peer review. Factors influencing the discussion activity are identified. It is observed that it is more difficult to obtain lively discussion when the number of contributed articles increases, which implies difficulties for scaling up the open peer review model. Suggestions are made for how this difficulty may be overcome.

We consider computer assisted troubleshooting of automotive vehicles, where the objective is to repair the vehicle at as low expected cost as possible.The work has three main contributions: a troubleshooting method that applies to troubleshooting in real environments, the discussion on practical issues in modeling for troubleshooting, and the efficient probability computations.The work is based on a case study of an auxiliary braking system of a modern truck.We apply a decision theoretic approach, consisting of a planner and a diagnoser.Two main challenges in troubleshooting automotive vehicles are the need for disassembling the vehicle during troubleshooting to access parts to repair, and the difficulty to verify that the vehicle is fault free. These facts lead to that probabilities for faults and for future observations must be computed for a system that has been subject to external interventions that cause changes the dependency structure. The probability computations are further complicated due to the mixture of instantaneous and non-instantaneous dependencies.To compute the probabilities, we develop a method based on an algorithm, <em>updateBN</em>, that updates a static BN to account for the external interventions.

We consider a constrained optimization problem with mixed integer and real variables. It models optimal placement of communications relay nodes in the presence of obstacles. This problem is widely encountered, for instance, in robotics, where it is required to survey some target located in one point and convey the gathered information back to a base station located in another point. One or more unmanned aerial or ground vehicles (UAVs or UGVs) can be used for this purpose as communications relays. The decision variables are the number of unmanned vehicles (UVs) and the UV positions. The objective function is assumed to access the placement quality. We suggest one instance of such a function which is more suitable for accessing UAV placement. The constraints are determined by, firstly, a free line of sight requirement for every consecutive pair in the chain and, secondly, a limited communication range. Because of these requirements, our constrained optimization problem is a difficult multi-extremal problem for any fixed number of UVs. Moreover, the feasible set of real variables is typically disjoint. We present an approach that allows us to efficiently find a practically acceptable approximation to a global minimum in the problem of optimal placement of communications relay nodes. It is based on a spatial discretization with a subsequent reduction to a shortest path problem. The case of a restricted number of available UVs is also considered here. We introduce two label correcting algorithms which are able to take advantage of using some peculiarities of the resulting restricted shortest path problem. The algorithms produce a Pareto solution to the two-objective problem of minimizing the path cost and the number of hops. We justify their correctness. The presented results of numerical 3D experiments show that our algorithms are superior to the conventional Bellman-Ford algorithm tailored to solving this problem.

This contribution aims at unifying two recent trends in applied particle filtering (PF). The first trend is the major impact in simultaneous localization and mapping (SLAM) applications, utilizing the FastSLAM algorithm. Thesecond one is the implications of the marginalized particle filter (MPF) or the Rao-Blackwellized particle filter (RBPF) in positioning and tracking applications. Using the standard FastSLAM algorithm, only low-dimensional vehicle modelsare computationally feasible. In this work, an algorithm is introduced which merges FastSLAM and MPF, and the result is an algorithm for SLAM applications, where state vectors of higher dimensions can be used. Results using experimental data from a UAV (helicopter) are presented. The algorithmfuses measurements from on-board inertial sensors (accelerometer and gyro) and vision in order to solve the SLAM problem, i.e., enable navigation over a long period of time.

The newly appeared Handbook of Knowledge Representation is an impressive piece of work. Its three editors and its forty-five contributors have produced twenty-five concise, textbook-style chapters that introduce most of the major aspects of the science of knowledge representation. Reading this book is a very positive experience: it demonstrates the breadth, the depth and the coherence that our field has achieved by now.

We study the problem of positioning unmanned aerial vehicles (UAVs) to maintain an unobstructed flow of communication from a surveying UAV to some base station through the use of multiple relay UAVs. This problem can be modeled as a hopconstrained shortest path problem in a large visibility graph. We propose a dual ascent method for solving this problem, optionally within a branch-and-bound framework. Computational tests show that realistic problems can be solved in a reasonably short time, and that the proposed method is faster than the classical dynamic programming approach.

he National Conference on Artificial Intelligence remains the bellwether for research in artificial intelligence. Leading AI researchers and practitioners as well as scientists and engineers in related fields present theoretical, experimental, and empirical results, covering a broad range of topics that include principles of cognition, perception, and action; the design, application, and evaluation of AI algorithms and systems; architectures and frameworks for classes of AI systems; and analyses of tasks and domains in which intelligent systems perform. The Innovative Applications of Artificial Intelligence conference highlights successful applications of AI technology; explores issues, methods, and lessons learned in the development and deployment of AI applications; and promotes an interchange of ideas between basic and applied AI. This volume presents the proceedings of the latest conferences, held in July, 2006.

I huvudsak kvinnliga studenter från elektro- och dataprogrammen och lä-rarutbildningen utbildades i genuskunskap och fick i uppdrag att under ett läsår studera sina utbildningar ur ett genusperspektiv gällande inne-håll, kurslitteratur, undervisnings- och examinationsformer samt bemö-tande från lärare och andra studenter. Studenterna från respektive utbild-ningsområde bildade var sin projektgrupp under ledning av en handledare.De huvudsakliga resultaten är dels att de kvinnliga studenterna efter utbildningen i genuskunskap och alla diskussioner ser sina utbildningar på ett nytt sätt, genom att självmant observera och reflektera över förete-elser de inte varit medvetna om. Dels har vi fått ökad kunskap om genus-aspekter i själva utbildningsprogrammen genom de observationer som studenterna gjort under läsåret. Dessutom kan man se projektet som en mall för andra program som man vill studera och genomlysa ur ett ge-nusperspektiv. Ett annat intressant resultat från projektet var bildandet av det kvinnliga nätverket Grace för elektro- och datastudenterna.<em>Rapporten beskriver projektet, dess uppläggning och genomförande, re-sultaten från respektive utbildningsområde och avslutas med en reflektion av projektet och de funna resultaten i ett större perspektiv med jämförelser med resultat från andra undersökningar om genus i högskoleutbildning.</em>

In this article we address the question of design principles for software individuals, and approach it as a software design issue. We use the term 'software individuals' to designate aggregates of programs and data that have the following properties.They exist in a population of similar but not identical in dividuals.Individuals are able to interact with their surrounding environment, with each other, and/or with people. While doingso they may modify their internal state.Each individual contains the safeguards that may be re quired in order to select which in uences to accomodateand which ones to ignore.The aggregate of programs and data that de ne an individual, and that in particular define its behavior, is a part ofits internal state and can therefore be modified as the result of the interactions where the individual is involved.Individuals or small groups of individuals are able to create new individuals that inherit the features of their parents.The program/data aggregate that dfi nes an individual is symbolic in character. The ability for knowledge represen tation is designed into individuals from the start.

This volume addresses all current aspects of relational methods and their applications in computer science. It presents a broad variety of fields and issues in which theories of relations provide conceptual or technical tools. The contributions address such subjects as relational methods in programming, relational constraints, relational methods in linguistics and spatial reasoning, relational modelling of uncertainty. All contributions provide the readers with new and original developments in the respective fields.The reader thus gets an interdisciplinary spectrum of the state of the art of relational methods and implementation-oriented solutions of problems related to these areas

This report describes a control system which enables the user to control a helicopter using a high level control language called FCL (Flight Control Language).

This report contains a derivation of a dynamic model of a helicopter.

This paper contains a derivation of a dynamic model of an aircraft.

Every intelligent agent embedded in physical environments needs the ability to connect, or anchor, the symbols used to perform abstract reasoning to the physical entities which these symbols refer to. However, there appears to be no general definition of this ability, nor of the principles that characterize it, in the context of autonomous embedded systems. In this paper, we do the first steps toward a definition of the concept of anchoring and its functionalities. We also outline a few difficulties of anchoring: the need to deal with indexical and objective references, definite and indefinite identifiers; the temporary impossibility to percept physical entities; and the need to rely on sensor data which is inherently affected by uncertainty and ambiguities. We illustrate the use of anchoring in two domains: an autonomous airborne vehicle for traffic surveillance, and a mobile ground vehicle performing navigation tasks.

Computer vision systems used in autonomous mobile vehicles are typically linked to higher-level deliberation processes. One important aspect of this link is how to connect, or anchor, the symbols used at the higher level to the objects in the vision system that these symbols refer to. Anchoring is complicated by the fact that the vision data are inherently affected by uncertainty. We propose an anchoring technique that uses fuzzy sets to represent the uncertainty in the perceptual data. We show examples where this technique allows a deliberative system to reason about the objects (cars) detected by a vision system embarked in an unmanned helicopter, in the framework of the Witas project.

The report is description of the ENSYM Project Oriented Studies(POS) of spring 1998. The project goal was to control a toy cararound a not beforehand given track as fast as possible.

Computer vision systems used in autonomous mobile vehicles are typically linked to higher-level deliberation processes. One important aspect of this link is how to connect, or anchor, the symbols used at the higher level to the objects in the vision system that these symbols refer to. Anchoring is complicated by the fact that the vision data are inherently affected by uncertainty. We propose an anchoring technique that uses fuzzy sets to represent the uncertainty in the perceptual data. We show examples where this technique allows a deliberative system to reason about the objects (cars) detected by a vision system embarked in an unmanned helicopter, in the framework of the Witas project.

Cognitive Robotics Logic (CRL) is an extensible logic language for characterizing actions and change, in particular for use in cognitive robotics. Its development emphasizes the issues of syntax, expressivity, underlying semantics and entailment methods (defined in terms of the semantics). Development of proof methods is de-emphasized. The salient results from this approach refer to the range of applicability and other related properties of the entailment methods. These results constitute a metatheory of actions and change.CRL is syntactically defined as a base language and a surface language. The base language is characterized by the following aspects:its three major predicates Holds, Occurs, and Occlude , which provide coherence when the language is extended;its reportoire of categorial functions, which is augmented when additional expressiveness is required in the language.The surface language provides additional notational convenience, and is defined by translation to the base language. The range of expressivity includes actions with duration, nondeterministic actions, actions in hybrid worlds with piecewise continuous fluents, some forms of ramification and causation, imprecise sensors and actuators, action failure, and some aspects of goal-directed agent behavior. Entailment methods are functions that map scenario descriptions to sets of intended models. They are defined using a reportoire of set-theoretic operations on sets of formulas and sets of models, including but not restricted to minimizing a set of models with respect to a preference relation. A progression of underlying semantics is defined, beginning with the partial state-transition semantics and its immediate generalization, the trajectory semantics. These underlying semantics are used for the formal analysis of the range of applicability of various entailment methods, including both those proposed by the others in this research, and those that developed in the course of the present work. The present reference article summarizes notation and definitions, so that forthcoming articles can refer to it for that purpose. It does not report on the results that have been obtained with the present approach, except insofar as it is needed for putting the notation into perspective.

The purpose of this article is to provide a uniform, lightweight language specification and tutorial for a class of temporal logics for reasoning about action and change that has been developed by our group during the period 1994-1998. The class of logics are collected under the name TAL, an acronym for Temporal Action Logics. TAL has its origins and inspiration in the work with Features and Fluents (FF) by Sandewall, but has diverged from the methodology and approach through the years. We first discuss distinctions and compatibility with FF, move on to the lightweight language specification, and then present a tutorial in terms of an excursion through the different parts of a relatively complex narrative defined using TAL. We conclude with an annotated list of published work from our group. The article tries to strike a reasonable balance between detail and readability, making a number of simplifications regarding narrative syntax and translation to a base logical language. Full details are available in numerous technical reports and articles which are listed in the final section of this article.

We propose an approach to modeling delayed effects of actions which is based on the use of causal constraints and their interaction with the direct effects of actions. The approach extends previous work with a causal approach used to deal with the ramification problem. We show the similarity between solutions to the modeling of indirect effects and delayed effects of actions by example. The base logic PMON+ is a temporal logic for reasoning about action and change and uses circumscription. It is shown that the extension for delayed effects of actions retains the first-order reducibility property shown previously for successfully dealing with the frame and ramification problems for a large class of action scenarios. We also consider the “causal qualification� problem, \"natural death\" of fluents and causal lag, each of which is closely related to the use of delayed effects.

<strong></strong> We propose an approach to modeling delayed effects of actions which is based on the use of causal constraints and their interaction with the direct effects of actions. The approach extends previous work with a causal approach used to deal with the ramification problem. We show the similarity between solutions to the modeling of indirect effects and delayed effects of actions by example. The base logic PMON+ is a temporal logic for reasoning about action and change and uses circumscription. It is shown that the extension for delayed effects of actions retains the first-order reducibility property shown previously for successfully dealing with the frame and ramification problems for a large class of action scenarios. We also consider the “causal qualification� problem, \"natural death\" of fluents and causal lag, each of which is closely related to the use of delayed effects.

This report describes the current state of work with PMON, a logic for reasoning about actions and change, and its extensions. PMON has been assessed correct for the K-IA class using Sandewall's Features and Fluents framework which provides tools for assessing the correctness of logics of action and change. A syntactic characterization of PMON has previously been provided in terms of a circumscription axiom which is shown to be reducible to a first-order formula. This report introduces a number of new extensions which are also reducible and deal with ramification. This report is intended to provide a formal specification of the PMON family of logics and the surface language L(SD) used to represent action scenario descriptions. It should be considered a working draft. The title of the report has a version number because both the languages and logics are continually evolving. Since this document is intended as a formal specification which is used by our group as a reference for research and implementation, it is understandably brief as regards intuitions and applications of the language and logics defined. We do provide a set of benchmarks and comments concerning these which can serve as a means of comparing this formalism with others. The set of benchmarks is not complete and is only intended to provide representative examples of the expressivity and use of this particular family of logics. We describe its features and limitations in other publications by our group which can normally be found at http://www.ida.liu.se/labs/kplab/.

We address the problem of characterizing goal-directed robotic behavior using a logic of actions and change. Our approach is based on distinguishing two kinds of actions: procedural actions which are defined in a mechanistic way, and goal-directed actions which are performed through a process involving tries, possibly failures, and corrective action and new tries until the goal has been reached. (The definition of procedural actions may be done external to the logic, for example through differential equations, or through a conventional programming language). For both kinds of actions, the logic expresses explicitly whether the action succeeds or fails. Each execution of a goal-directed action is also characterized by a number of breakpoints where some sub-action has been completed and a new sub-action for getting to the desired goal is selected. The logic is used for characterizing the selection of sub-actions at breakpoints, and the success or failure of the goal-directed action in terms of the success or failure of the sub-actions. The article describes how goal-directed actions can be modelled by an extension of existing results on logics of actions and change.

Recently, a great deal of progress has been made using nonmonotonic temporal logics to formalize reasoning about action and change. In particular, much focus has been placed on the proper representation of non-deterministic actions and the indirect effects of actions. One popular approach to representing the indirect effects of actions has been via the use of causal rules which in a more general sense can be viewed as fluent dependency constraints. Although fluent dependency constraints have been used primarily under a loose causal interpretation, we show that when interpreted in a broader sense they provide a flexible means for dealing with a number of other representational problems such as the qualification problem and the ramification constraints as qualification constraints problem, in addition to the standard ramification problem. More importantly, the use of fluent dependency constraints for different purposes does not involve additions to the base nonmonotonic temporal logic, TAL, used here, but simply the addition of several macro operators to an action language used to represent action scenarios or narratives. The payoff is that TAL has already been shown to offer a robust approach to representing action scenarios which permit incomplete specifications of both state and the timing of actions, non-deterministic actions, actions with duration, concurrent actions, use of both boolean and non-boolean fluents, and solutions to the frame and ramification problems for a wide class of action scenarios. In addition, all circumscribed action scenarios in these classes and the more general class involving qualification considered in this paper can be shown to be reducible to the first-order case. Finally, a restricted entailment method for this new class of scenarios is fully implemented. In the paper, we present a challenge example which incorporates all these features, propose a distinction between weak and strong qualification with a representation of both, and provide a visualization of the preferred entailments using a research tool VITAL for querying and visualizing action scenarios.

In this paper we present TAL-C, a logic of action and change for multi-agent environments which has a first-order semantics and proof theory. It is demonstrated how TAL-C can represent (cases of) a number of phenomena related to action concurrency: action duration, interference between one action's effects and another action's execution, bounds on concurrency, and conflicting, synergistic and cumulative effects of concurrent actions. A central idea is that most of the dynamics of the world is encoded in dependency laws relating to specific features instead of encoded directly in action laws. Thus, treatment of different types of interaction can be customized for specific features.

In this paper we present some preliminary results regarding a system for developing autonomous agents that combine reactivity to an uncertain and rapidly changing environment and commitment to prespecified tactics involving cooperation. A central requirement is that the behavior specification should be done by people who are not computer and AI specialists. The original application was air-combat simulation. Here we consider the simulated soccer domain in perspective of the RoboCup competition. The behavior of an agent is specified in terms of prioritized rules organized into a decision tree. Coordinated behaviors are encoded in the decision trees of the individual agents. What link individual behavior descriptions together are explicit communication and common means to describe the situation the agents are in.

I propose a <em>neo-classical</em> structure for publishing and reviewing of scientific works. This proposal has the following characteristic components:<ul><li>Electronic “preprint archives� and other similar mechanisms where research articles are made publicly available without prior formal review are considered as true and full-fledged <em>publication</em> of research from the point of view of priority of results.</li><li>Large parts of the reviewing process is done publicly and in the form of published review letters and other contributions to the scientific debate, rather than through anonymous and confidential review statements which dominate today. There is a switch from anonymous “pass-fail� reviewing towards <em>open reviewing</em> where the identity and the comments of the reviewers are made public.</li><li>Since open reviewing happens <em>after</em> publication, rather than before, there is a second step where articles are promoted to “recommended� or “certified� status through the decision of a review committee. The requirements for certification are set at least as high as for the formally published journal articles of today, so that it counts like journal publication in a CV.</li><li>Several techniques are foreseen for facilitating the selection process of the individual reader as well as for improving communication as such between researchers.</li><li>One should accept that there are good reasons why there may be several articles (from the same author) presenting the same result. This suggests the introduction of a formal concept of a “result� which is represented by several publications, and to allow citations to refer to results rather than to some specific publication of the result.</li></ul>I refer to this system as <em>neo-classical</em> because it assumes that peer review is done <em>openly</em> and <em>after</em> an article has been published. It is of course only proposed as a complement which can easily co-exist with the modern system, allowing each author to choose which of the two systems he or she wishes to use for a particular article.

We address the problem of formally proving high-level effect descriptions of actions from low-level operational definitions. Both descriptions are expressed in a logic of actions and change, with extensions for characterizing continuous change, discontinuities, the distinction between true and estimated values of state variables, and the distinction between success and failure of an action. Both descriptions also require the use of nonmonotonicity in the logic in question. The transition from operational definition to effect description furthermore involves the creation of a closure with respect to the set of possible ways that the action can fail.We outline, by means of an example, how these issues can be addressed as an extension of existing results on logics of actions and change

An underlying semantics for propagation oriented ramification, called causal propagation semanticsComparative assessments of a number of previously proposed entailment methods for ramification, in particular, methods based on minimization of change after partitioning of the state variables (fluents). This includes the methods previously proposed by del Val and Shoham, by Kartha and Lifschitz, and by our group.Assessment of two ranges of sound applicability for one of those entailment methods, MSCC, relative to causal propagation semantics.Identification of an essential feature for minimization-based approaches to ramification, namely changeset-partitioning.

This article reports on assessment results for several approaches to the ramification problem. Two types of assessments are reported: (1) Assessment of soundness for one minimization based and one causation-based method; (2) Relative range assessments for a number of minimization based methods. Assessment of soundness is based on an underlying semantics for ramification. We propose, define, and use a \emp{causal propagation} semantics for this purpose. Causal propagation means that an action is viewed as consisting of an initial state transition which represents the invocation of the action, followed by a succession of other state transitions which may be understood as representing links in a causal chain. The assessment of an entailment method specifies restrictions on the invocation and causation relations which guarantee that the entailment method is sound. Relative range assessments compare entailment methods pairwise and specify whether the set of selected models obtained by one is a subset of the set of selected models obtained by the other.

Linköping University has recently created a separate entity, called <em>Linköping University Electronic Press</em>, for the <em>unrefereed electronic publication</em> of research articles and other university-related materials over the Internet. The present article presents the background for why the E-Press was created and the strategies which have been chosen for its operation at least during its initial period. The article identifies three key problems in the context of this strategy:<ul><li>The purely <em>formal problems</em> concerning what counts as a publication;</li><li>The <em>persistence problem</em> of making sure that an electronically published article does not change over time;</li><li>The <em>reception problems</em> concerning how fellow researchers and the academic community regard electronically published articles.</li></ul>We describe how the formal problems and the persistence problems have been addressed in the E-Press initiative. With respect to the reception problems, we argue that scientific journals and journal-like conferences presently perform four distinct functions, and that these functions can be performed better if they are \"unbundled\" and addressed by other means. The four functions are:<ul><li>Publication in the narrow sense - making the article publicly available;</li><li>Scientific quality control through reviewing;</li><li>Selection of relevant articles for the benefit of the researcher-reader;</li><li>Promotion of the scientific results of the author.</li></ul>The Electronic Press focusses on the first one of these four functions. We discuss how the other three functions can be separated and performed by other means than through a conventional journal or quality conference proceedings.

This report describes the current state of work with PMON, a logic for reasoning about action and change, and its extensions. PMON has been assessed correct for the K-IA class using Sandewall's Features and Fluents framework which provides tools for assessing the correctness of logics of action and change. A syntactic characterization of PMON has previously been provided in terms of a circumscription axiom which is shown to be reducible to a first-order formula. This report introduces a number of new extensions which are also reducible and deal with ramification. The report is intended to provide a formal specification for the PMON family of logics and the surface language L(SD) used to represent action scenario descriptions. It should be considered a working draft. The title of the report has a version number because both the languages and logics used are continually evolving. Since this document is intended as a formal specification which is used by our group as a reference for research and implementation, it is understandably brief as regards intuitions and applications of the languages and logics defined. We do provide a set of benchmarks and comments concerning these which can serve as a means of comparing this formalism with others. The set of benchmarks is not complete and is only intended to provide representative examples of the expressivity and use of this particular family of logics. We describe its features and limitations in other publications by our group which can normally be found at \"http://www.ida.liu.se/labs/kplab/\".

In this paper, we propose a new way of considering reasoning about action and change. Rather than placing a preferential structure onto the models of logical theories, we place such a structure directly on the semantics of the actions involved. In this way, we obtain a preferential semantics of actions by means of which we can not only deal with several of the traditional problems in this area such as the frame and ramification problems, but can generalize these solutions to a context which includes both nondeterministic and concurrent actions. In fact, the net result is an integration of semantical and verificational techniques from the paradigm of imperative and concurrent programs in particular, as known from traditional programming, with the AI perspective. In this paper, the main focus is on semantical (i.e. model theoretical) issues rather than providing a logical calculus, which would be the next step in the endeavor.

Time and logic are central driving concepts in science and technology. In this book, some of the major current developments in our understanding and application of temporal logic are presented in computational terms. \"Time and Logic: A Computational Approach\" should be a useful sourcebook for those within the specific field of temporal logic, as well as providing valuable introductory material for those seeking an entry into this increasingly important area of theoretical computing.; The emphasis of the book is on presenting a broad range of approaches to computational applications. The techniques used will also be applicable in many cases to formalize beyond temporal logic alone, and it is hoped that adaptation to many different logics of programmes will be facilitated. Throughout, the authors have kept implementation-oriented solutions in mind.; The book begins with an introduction to the basic ideas of temporal logic. Successive chapters then examine particular aspects of the temporal theoretical computing domain, relating their applications to familiar areas of research, such as stochastic process theory, automata theory, established proof systems, model checking, relational logic and classical predicate logic. This should be a useful addition to the library of all theoretical computer scientists, providing a synthesis of well established results in temporal logic with the most up-to-date findings of some of the world's leading theoreticians.

In recent years, a great deal of attention has been devoted to logics of \"commonsense\" reasoning. Among the candidates proposed, circumscription has been perceived as an elegant mathematical technique for modeling nonmonotonic reasoning, but difficult to apply in practice. The major reason for this is the nd-order nature of circumscription axioms and the difficulty in finding proper substitutions of predicate expressions for predicate variables. One solution to this problem is to compile, where possible, nd-order formulas into equivalent 1st-order formulas. Although some progress has been made using this approach, the results are not as strong as one might desire and they are isolated in nature. In this article, we provide a general method which can be used in an algorithmic manner to reduce circumscription axioms to 1st-order formulas. The algorithm takes as input an arbitrary 2nd-order formula and either returns as output an equivalent 1st-order formula, or terminates with failure. The class of 2nd-order formulas, and analogously the class of circumscriptive theories which can be reduced, provably subsumes those covered by existing results. We demonstrate the generality of the algorithm using circumscriptive theories with mixed quantifiers (some involving Skolemization), variable constants, non-separated formulas, and formulas with n-ary predicate variables. In addition, we analyze the strength of the algorithm and compare it with existing approaches providing formal subsumption results.

In this paper, we consider the problem of partitioning a polygon into a set of connected disjoint sub-polygons, each of which covers an area of a specific size. The work is motivated by terrain covering applications in robotics, where the goal is to find a set of efficient plans for a team of heterogeneous robots to cover a given area. Within this application, solving a polygon partitioning problem is an essential stepping stone. Unlike previous work, the problem formulation proposed in this paper also considers a compactness metric of the generated sub-polygons, in addition to the area size constraints. Maximizing the compactness of sub-polygons directly influences the optimality of any generated motion plans. Consequently, this increases the efficiency with which robotic tasks can be performed within each sub-region. The proposed problem representation is based on grid cell decomposition and a potential field model that allows for the use of standard optimization techniques. A new algorithm, the AreaDecompose algorithm, is proposed to solve this problem. The algorithm includes a number of existing and new optimization techniques combined with two post-processing methods. The approach has been evaluated on a set of randomly generated polygons which are then divided using different criteria and the results have been compared with a state-of-the-art algorithm. Results show that the proposed algorithm can efficiently divide polygon regions maximizing compactness of the resulting partitions, where the sub-polygon regions are on average up to 73% more compact in comparison to existing techniques.