Searching minimax game trees under memory space constraint

Games such as CHESS, GO and OTHELLO can be represented by minimax game trees. Among various search procedures to solve such game trees,- and SSS^* are perhaps most well known. Although it is proved that SSS^* explores only a subset of the nodes explored by-, - is commonly believed to be faster in real applications, since it requires very little memory space and hence its storage management cost is low. Contrary to this folklore, however, this paper reports, using the OTHELLO game as an example, that SSS^* is much faster than-. It is also demonstrated that SSS^* can be modified to make the required memory space controllable to some extent, while retaining the high efficiency of the original SSS^*.This research was partially supported by the Ministry of Education, Science and Culture of Japan, under a Scientific Grant-in-Aid.     

Enhancing the performance of an agent-based manufacturing system through learning and forecasting

Agent-based technology has been identified as an important approach for developing next generation manufacturing systems. One of the key techniques needed for implementing such advanced systems will be learning. This paper first discusses learning issues in agent-based manufacturing systems and reviews related approaches, then describes how to enhance the performance of an agent-based manufacturing system through learning from history (based on distributed case-based learning and reasoning) and learning from the future (through system forecasting simulation). Learning from history is used to enhance coordination capabilities by minimizing communication and processing overheads. Learning from the future is used to adjust promissory schedules through forecasting simulation, by taking into account the shop floor interactions, production and transportation time. Detailed learning and reasoning mechanisms are described and partial experimental results are presented.     

Sense-controlled flexible robot behavior

The creation of physical behavior by computational means has been approached differently by industrial and artificial intelligence robotics. Industrial robotics, considering fast response of a robot its most important characteristic, has equipped the robot with predefined, specific behavioral trajectories resulting in fast but inflexible behavior. Artificial intelligence robotics, claiming flexibility as the paramount robot feature, has employed inferred behavior whereby the robot itself determines behavioral patterns for tasks based on the robot's general knowledge about a task domain. Response is now flexible, but the response time is commonly badly degraded. This work defines an action propensity skill which generates flexibleand fast behavior. Flexibility is achieved by attaching perceptions in skills to guide behavior; fast response results from the direct activation of skills. The acquisition and generalization of skills happens under the supervision of a human teacher in an advice-taking mode into which the robot shifts from the execution mode after recognizing lacking competence for a given task. This paper defines such skills, describes an implemented skilled robot system, and discusses some simulation results.     

Logic Based Abstractions of Real-Time Systems

When verifying concurrent systems described by transition systems, state explosion is one of the most serious problems. If quantitative temporal information (expressed by clock ticks) is considered, state explosion is even more serious. We present a notion of abstraction of transition systems, where the abstraction is driven by the formulae of a quantitative temporal logic, called qu-mu-calculus, defined in the paper. The abstraction is based on a notion of bisimulation equivalence, called , n-equivalence, where is a set of actions and n is a natural number. It is proved that two transition systems are , n-equivalent iff they give the same truth value to all qu-mu-calculus formulae such that the actions occurring in the modal operators are contained in , and with time constraints whose values are less than or equal to n. We present a non-standard (abstract) semantics for a timed process algebra able to produce reduced transition systems for checking formulae. The abstract semantics, parametric with respect to a set of actions and a natural number n, produces a reduced transition system , n-equivalent to the standard one. A transformational method is also defined, by means of which it is possible to syntactically transform a program into a smaller one, still preserving , n-equivalence.     

A variotherm mold for micro metal injection molding

In this paper, a variotherm mold was designed and fabricated for the production of 316L stainless steel microstructures by micro metal injection molding (MIM). The variotherm mold incorporated a rapid heating/cooling system, vacuum unit, hot sprue and cavity pressure transducer. The design of the variotherm mold and the process cycle of MIM using the variotherm mold were described. Experiments were conducted to evaluate the molded microstructures produced using variotherm mold and conventional mold. The experiments showed that microstructures of higher aspect ratio such as 60 m × height 191 m and 40 m × height 174 m microstructures could be injection molded with complete filling and demolded successfully using the variotherm mold. Molded microstructures with dimensions of 60 m × height 191 m were successfully debound and sintered without visual defects.     

Modelling the student in Pitagora 2.0

With the aim to individualise human-computer interaction, an Intelligent Tutoring System (ITS) has to keep track of what and how the student has learned. Hence, it is necessary to maintain a Student Model (SM) dealing with complex knowledge representation, such as incomplete and inconsistent knowledge and belief revision. With this in view, the main objective of this paper is to present and discuss the student modelling approach we have adopted to implement Pitagora 2.0, an ITS based on a co-operative learning model, and designed to support teaching-learning activities in a Euclidean Geometry context. In particular, this approach has led us to develop two distinct modules that cooperate to implement the SM of Pitagora 2.0. The first module resembles a classical student model, in the sense that it maintains a representation of the current student knowledge level, which can be used by the teacher in order to tune its teaching strategies to the specific student needs. In addition, our system contains a second module that implements a virtual partner, called companion. This module consists of a computational model of an average student which cooperates with the student during the learning process. The above mentioned module calls for the use of machine learning algorithms that allow the companion to improve in parallel with the real student. Computational results obtained when testing this module in simulation experiments are also presented.     

From Conditional Events to Conditional Measures: A New Axiomatic Approach

Our starting point is a definition of conditional event EH which differs from many seemingly similar ones adopted in the relevant literature since 1935, starting with de Finetti. In fact, if we do not assign the same third value u (undetermined) to all conditional events, but make it depend on EH, it turns out that this function t(EH) can be taken as a general conditional uncertainty measure, and we get (through a suitable – in a sense, compulsory – choice of the relevant operations among conditional events) the natural axioms for many different (besides probability) conditional measures.     

On realization of nonlinear systems described by higher-order differential equations

We consider systems of smooth nonlinear differential and algebraic equations in which some of the variables are distinguished as external variables. The realization problem is to replace the higher-order implicit differential equations by first-order explicit differential equations and the algebraic equations by mappings to the external variables. This involves the introduction of state variables. We show that under general conditions there exist realizations containing a set of auxiliary variables, called driving variables. We give sufficient conditions for the existence of realizations involving only state variables and external variables, which can then be split into input and output variables. It is shown that in general there are structural obstructions for the existence of such realizations. We give a constructive procedure to obtain realizations with or without driving variables. The realization procedure is also applied to systems defined by interconnections of state space systems. Finally, a theory of equivalence transformations of systems of higher-order differential equations is developed.     

States and the free orthogonality monoid

Let (X, #) be an orthogonality space such that the lattice C(X, #) of closed subsets of (X, #) is orthomodular and let (, ) denote the free orthogonality monoid over (X, #). Let C₀(, ) be the subset of C(, ), consisting of all closures of bounded orthogonal sets. We show that C₀(, ) is a suborthomodular lattice of C(, ) and we provide a necessary and sufficient condition for C₀(, ) to carry a full set of dispersion free states.The work of the second author on this paper was supported by National Science Foundation Grant GP-9005.     

PDAs and shared public displays: Making personal information public, and public information personal

We are investigating how people move from individual to group work through the use of both personal digital assistants (PDAs) and a shared public display. Our scenario of this work covers the following activities. First, mobile individuals can create personal notes on their PDAs. Second, when individuals meet in real time, they can selectively publicise notes by moving them to a shared public display. Third, the group can manipulate personal and public items in real time through both PDAs and the shared public display, where the notes contained on both PDAs and public display are automatically synchronised. Finally, people leave a meeting with a common record of their activity. We describe our SharedNotes system that illustrates how people move through this scenario. We also highlight a variety of problematic design issues that result from having different devices and from having the system enforce a rigid distinction between personal and public information.     

Reasoning about the Elementary Functions of Complex Analysis

There are many problems with the simplification of elementary functions, particularly over the complex plane, though not exclusively – see (20). Systems tend to make howlers or not to simplify enough. In this paper we outline the unwinding number approach to such problems, and show how it can be used to prevent errors and to systematise such simplification, even though we have not yet reduced the simplification process to a complete algorithm. The unsolved problems are probably more amenable to the techniques of artificial intelligence and theorem proving than the original problem of complex-variable analysis.     

A formal model of atomicity in asynchronous systems

Summary We propose a generalisation of occurrence graphs as a formal model of computational structure. The model is used to define the atomic occurrence of a program, to characterise interference freeness between programs, and to model error recovery in a decentralised system.     

Unitary immersions of nonlinear systems

In this paper, we define what we call a unitary immersion of a nonlinear system. We observe that, for classical Hamiltonian systems, this notion contains, in some sense, the concept of quantization. We restrict our attention to degree-zero unitary immersions, where all observation functions must be represented by operators of the type multiplication by a function. We show that the problem of classifying such degree-zero unitary immersions of a given nonlinear system is not obvious. In some cases, we solve this problem.Chargé de Recherche au CNRS.Maître de Conférences.     

Modeling Robot “Psycho-Physical” State and Reactions – A New Option in Human–Robot Communication Part 1: Concept and Background

Man–machine communication had been recognized a long time ago as a significant issue in the implementation of automation. It influences the machine effectiveness through direct costs for operator training and through more or less comfortable working conditions. The solution for the increased effectiveness might be found in user-friendly human–machine interface. In robotics, the question of communication and its user-friendliness is becoming even more significant. It is no longer satisfactory that a communication can be called human–machine interface, since one must see robots as future collaborators, service workers, and probably personal helpers. So, a new way of communication is needed. This paper starts from the fact that a variety of unconventional ways of communication is being explored: speech communication, handwriting, and facial mimicry. Speech recognition and generation, apart from its potentially strong impact to human–robot interface, is out of the scope of this study, and the same holds for handwriting. The facial mimicry and the wider field of robot emotion lead to a new way of communication that can be called gestural language. We may say that our research matches such a wide notion. However, there is an important specificity of our approach. Previous works in this field looked at facial and gestural expressions of emotions and messages as actually voluntary activities. They were induced by some situations, but such situations had to be recognized after which the appropriate preprogrammed reaction followed. Thus, some expert system or other artificial intelligence system were applied. The current study explores the conditional reactions that are chemically based. Human psycho-physical states like fear, stress and especially fatigue follow from complex chemical processes. Such states cannot be voluntarily controlled. They are not expressed through some specific mimicry or body movement, but they influence all movements. Any motion intended to accomplish some task will be changed, thus sending a message to the neighborhood. This change can be observed, and so the message is received. For processes of this kind and their resembling, we prefer using the term modeling psycho-physical states. Among various states interesting for application in robots, the present study concentrates on fatigue, which is a good example for the initial research. The first part of the paper explains the concept and the background, while the second part provides numerical justification.     

End-to-end communications management using TMN “X” interfaces

The ongoing integration of LANs and WANs to support global communications and businesses and the emergence of integrated broadband communication services has created an increased demand for cooperation between customers, network and service providers to achieve end-to-end service management. Such a cooperation between autonomous authorities, each defining their own administrative management domains, requires the application of an open standardized framework to facilitate and regulate interworking. Such a framework is given by the ITU-T recommendations on TMN, where the so-called X interface is of particular importance for inter-domain management. In this paper, we explain the role of the TMN X interface within an inter-domain TMN architecture supporting end-to-end communications management. We identify the important issues that need to be addressed for the definition and realization of TMN X interfaces and report about our practical experiences with the implementation of TMN X interfaces in the PREPARE project.     

Development of models of optimal complexity using self-organization theory

An organized approach is considered for determining the best functional (usually polynomial) form of a mathematical model for a complex system using the minimum ofa priori information. It is necessary to know only the list of the variables that may possibly take part in the model, the corresponding table of data, and the general criterion that the model is to satisfy (e.g., the prediction is to be accurate or the model is to be unbiassed). The computer, with the help of a special organized sifting of models, uses the self-organization principle to find a unique model of optimal complexity.     

Automated Deduction Techniques for the Management of Personalized Documents

This work is about a real-world application of automated deduction. The application is the management of documents (such as mathematical textbooks) as they occur in a readily available tool. In this Slicing Information Technology tool, documents are decomposed (sliced) into small units. A particular application task is to assemble a new document from such units in a selective way, based on the user's current interest and knowledge. It is argued that this task can be naturally expressed through logic, and that automated deduction technology can be exploited for solving it. More precisely, we rely on first-order clausal logic with some default negation principle, and we propose a model computation theorem prover as a suitable deduction mechanism. Beyond solving the task at hand as such, with this work we contribute to the quest for arguments in favor of automated deduction techniques in the real world. Also, we argue why we think that automated deduction techniques are the best choice here.     

Modeling Robot “Psycho-Physical” State and Reactions – A New Option in Human–Robot Communication Part 2: Modeling and Simulation

This part of the paper examines numerically the possibility of modeling robot fatigue being representative of a human psychophysical state that can be applied to robots. Temperatures of driving motors are suggested as analogs to fatigue in muscles. Simulation of robot behavior is performed on a typical human task, namely handwriting. Three phases of task execution, characteristic for humans, are observed, i.e. regular motion, reconfiguration after symptoms of fatigue, and degeneration caused by the too long, hard work.     

System Embedding. Linear Control with Observation

Linear control in the object-state observer-controller loop was considered. The matrix equations defining the general solution to this problem based on the desirable matrix transfer function were obtained using the technology of system embedding. In contrast to the traditional concept of separation of linear observation and control, the unknown auxiliary matrix appearing in these equations was shown to reflect their integration. An algorithm to design the united state observer-controller system from the desirable closed-loop matrix transfer functions was proposed. The paper was illustrated by examples.