Showing papers by "French Institute for Research in Computer Science and Automation published in 1989"
01 Dec 1989
TL;DR: A new kind of abstract machine based on the chemical metaphor used in the Γ language of Banâtre & al. is introduced, which shows how to extract a higher-order concurrent λ-calculus out of the basic concepts of the chemical abstract machine.
Abstract: We introduce a new kind of abstract machine based on the chemical metaphor used in the G language of Banâtre & al. States of a machine are chemical solutions where floating molecules can interact according to reaction rules. Solutions can be stratified by encapsulating subsolutions within membranes that force reactions to occur locally. We illustrate the use of this model by describing the operational semantics of the TCCS and CCS process calculi. We also show how to extract a higher-order concurrent l-calculus out of the basic concepts of the chemical abstract machine.
853 citations
TL;DR: It is found appropriate to use a diagonal matrix, generated by an update of the identity matrix, so as to fit the Rayleigh ellipsoid of the local Hessian in the direction of the change in the gradient.
Abstract: This paper describes some numerical experiments with variable-storage quasi-Newton methods for the optimization of some large-scale models (coming from fluid mechanics and molecular biology). In addition to assessing these kinds of methods in real-life situations, we compare an algorithm of A. Buckley with a proposal by J. Nocedal. The latter seems generally superior, provided that careful attention is given to some nontrivial implementation aspects, which concern the general question of properly initializing a quasi-Newton matrix. In this context, we find it appropriate to use a diagonal matrix, generated by an update of the identity matrix, so as to fit the Rayleigh ellipsoid of the local Hessian in the direction of the change in the gradient.
Also, a variational derivation of some rank one and rank two updates in Hilbert spaces is given.
719 citations
TL;DR: It is shown that a singular configuration is obtained when the variety spanned by the lines associated to the robot links has a rank less than 6 and a new method based on Grassmann line geometry is proposed, which finds all the well-known singular configurations, and also some new ones.
Abstract: Parallel manipulators have a specific mechanical architecture where all the links are connected both at the base and at the gripper of the robot. By changing the lengths of these links we are able to control the position1 of the gripper. In general, for a given set of links lengths there is only one position for the gripper. However, it may be suspected that in some cases more than one solution may be found for the position of the gripper: the robot is in a singular configuration. To determine these singular configurations the classical method is to find the roots of the determinant of the jacobian matrix. In our case the jacobian matrix is complex, and it seems not to be possible to find these roots. We propose here a new method based on Grassmann line geometry. The set of lines, P3, constitutes a linear variety of rank 6. We show that a singular configuration is obtained when the variety spanned by the lines associated to the robot links has a rank less than 6. An important feature of the varieties of t...
605 citations
01 Dec 1989
TL;DR: The λ&sgr;-calculus is a refinement of the λ-Calculus where substitutions are manipulated explicitly, and provides a setting for studying the theory of substitutions, with pleasant mathematical properties.
Abstract: The ls-calculus is a refinement of the l-calculus where substitutions are manipulated explicitly. The ls-calculus provides a setting for studying the theory of substitutions, with pleasant mathematical properties. It is also a useful bridge between the classical l-calculus and concrete implementations.
577 citations
01 Dec 1989
TL;DR: In this article, the authors present a tool called Extended Kalman Filter (EKF) for the problem of building and updating 3D representations of the environment of a mobile robot using passive vision as its main sensory modality.
Abstract: A description is given of current ideas related to the problem of building and updating three-dimensional representations of the environment of a mobile robot that uses passive vision as its main sensory modality. The authors attempt to represent both geometry and uncertainty. The authors motivate their approach by defining the problems they are trying to solve and then give some simple didactic examples. They then present a tool they think is extremely well adapted to solving most of these problems: the extended Kalman filter (EKF). The authors discuss the notions of minimal geometric representations for three-dimensional lines, planes, and rigid motions. They show how the EKF and the representations can be combined to provide solutions for some of the problems. A number of experimental results on real data are given. >
352 citations
TL;DR: It is shown in particular that, given any desired product mix, it is possible to start the system with enough jobs in process so that some machines will be fully utilized in steady-state and the productivity is optimal.
Abstract: Timed event-graphs, a special class of timed Petri nets, are used for modelling and analyzing job-shop systems. The modelling allows the steady-state performance of the system to be evaluated under a deterministic and cyclic production process. Given any fixed processing times, the productivity (i.e., production rate) of the system can be determined from the initial state. It is shown in particular that, given any desired product mix, it is possible to start the system with enough jobs in process so that some machines will be fully utilized in steady-state. These machines are called bottleneck machines, since they limit the throughput of the system. In that case, the system works at the maximal rate and the productivity is optimal. The minimal number of jobs in process allowing optimal functioning of the system is further specified as an integer linear programming problem. An efficient heuristic algorithm is developed to obtain a near-optimal solution. >
318 citations
03 Jan 1989
TL;DR: This work solves the problem of global treatment of record types as a special case by giving an ordinary status to records without any ad hoc assertions, replacing inclusion rules by extra information in record types.
Abstract: Strongly typed languages with records may have inclusion rules so that records with more fields can be used instead of records with less fields. But these rules lead to a global treatment of record types as a special case. We solve this problem by giving an ordinary status to records without any ad hoc assertions, replacing inclusion rules by extra information in record types. With this encoding ML naturally extends its polymorphism to records but any other host language will also transmit its power.
230 citations
TL;DR: This work proposes some rules for the transformation of equational problems and studies their correctness in various models and gives completeness results with respect to some ''simple'' problems called solved forms.
216 citations
TL;DR: In this article, the authors present an approximate method for the analysis of transfer lines with unreliable machines and finite buffers, which leads to a simple and fast algorithm which provides performance parameters such as production rate and average buffer levels.
Abstract: The authors present an approximate method for the analysis of transfer lines with unreliable machines and finite buffers. In these systems blocking and starvation, which occur as a consequence of machine failures, are important phenomena. They first consider homogeneous lines, i.e., lines for which all machines have the same processing times. The behavior of the line is approximated by a continuous flow model. They then use a decomposition technique which enables one to decompose the analysis of the line into the analysis of a set of two-machine lines. This leads to a simple and fast algorithm which provides performance parameters such as production rate and average buffer levels. Experimental results show that this approximate technique is very accurate. They then consider the case of transfer lines with machines having different processing times. A simple transformation is introduced which replaces the line by a homogeneous line. This approximate transformation provides good results for a large class of systems. >
212 citations
03 Jan 1989
TL;DR: This paper defines a notion of realizability for the Calculus of Constructions and introduces a distinction between informative and non-informative propositions that allows the removal of the “logical” part in the development of a program.
Abstract: We define in this paper a notion of realizability for the Calculus of Constructions. The extracted programs are terms of the Calculus that do not contain dependent types. We introduce a distinction between informative and non-informative propositions. This distinction allows the removal of the “logical” part in the development of a program. We show also how to use our notion of realizability in order to interpret various axioms like the axiom of choice or the induction on integers. A practical example of development of program is given in the appendix.
184 citations
TL;DR: In this paper, an approach that relies on modeling principles and likely hypothesis testing techniques is proposed for the determination of moving edges in an image sequence, where a spatio-temporal edge is modeled as a surface patch in a 3D spatiotemporal space.
Abstract: The determination of moving edges in an image sequence is discussed An approach is proposed that relies on modeling principles and likely hypothesis testing techniques A spatiotemporal edge in an image sequence is modeled as a surface patch in a 3-D spatiotemporal space A likelihood ratio test enables its detection as well as simultaneous estimation of its related attributes It is shown that the computation of this test leads to convolving the image sequence with a set of predetermined masks The emphasis is on a restricted but widely relevant and useful case of surface patch, namely the planar one In addition, an implementation of the procedure whose computation cost is merely equivalent to a spatial gradient operator is presented This method can be of interest for motion-analysis schemes, not only for supplying spatiotemporal segmentation, but also for extracting local motion information Moreover, it can cope with occlusion contours and important displacement magnitude Experiments have been carried out with both synthetic and real images >
TL;DR: The class of acyclic fork-join queuing networks that arise in various applications, including parallel processing and flexible manufacturing are studied and stability conditions are obtained and upper and lower bounds on the network response times are developed.
Abstract: In this paper the class of acyclic fork-join queuing networks that arise in various applications, including parallel processing and flexible manufacturing are studied. In such queuing networks, a fork describes the simultaneous creation of several new customers, which are sent to different queues. The corresponding join occurs when the services of all these new customers are completed. The evolution equations that govern the behavior of such networks are derived. From this, the stability conditions are obtained and upper and lower bounds on the network response times are developed. These bounds are based on various stochastic ordering principles and on the notion of association of random variables.
01 Jan 1989
TL;DR: The authors consider queueing that occur naturally in the study of a class of resource-sharing problems under synchronization constraints such as resequencing and fork-join primitives, which are amenable to a representation in terms of a state recursion.
Abstract: The authors consider queueing that occur naturally in the study of a class of resource-sharing problems under synchronization constraints such as resequencing and fork-join primitives These queueing models are amenable to a representation in terms of a state recursion The proposed methods of analysis are complementary and draw on classical ideas of queuing theory as well as on mathematical tools from the theory of stochastic ordering and ergodic theory The state recursion is at the center of all aspects of the analysis, be it for developing the exact solutions, obtaining bounds on system performance or establishing the stability conditions The ideas are illustrated on simple models of resequencing and fork-join synchronization, which emphasis put on deriving computable bounds on the performance measures >
01 Sep 1989
TL;DR: An efficient algorithm determining perspective structures such as vanishing points and horizon lines for indoor scenes for indoor Scenes as a hierarchical Hough transform on the pyramidal sphere is presented.
Book•
12 Jun 1989TL;DR: The advanced information management prototype Verso, a database machine based on nested relations, and an approach to manage large inheritance networks within a DBS supporting nested relations are presented.
Abstract: The advanced information management prototype.- Verso: A database machine based on nested relations.- The two roles of nested relations in the DASDBS project.- A storage structure for Nested Relational Databases.- Four views of complex objects: A sophisticate's introduction.- An introduction to the completeness of languages for complex objects and nested relations.- On the uniqueness of nested relations.- An introduction to the Nested Sequences of Tuples data model and algebra.- Recursively defined complex objects.- Query languages for Nested Relational Databases.- Nested relations and recursive queries.- Realization of nested relation interfaces for relational and network databases.- An approach to manage large inheritance networks within a DBS supporting nested relations.- On the normalization in Nested Relational Databases.- Complex objects modeling: An entity-relationship approach.- A data model for complex objects based on a semantic database model and nested relations.- ?-Acyclic database schemes and nested relations.
TL;DR: The probability is √2/3 + O(n −1/3 ) that the graph has no components with more than one cycle at the moment when the number of edges passes ½ n and the results can be proved with analytical methods based on combinatorial enumeration with multivariate generating functions, followed by contour integration to derive asymptotic formulas for the quantities of interest.
29 Mar 1989
TL;DR: It is shown that all primitive recursive functionals over these inductively defined types are also representable, and it is sketched some results that show that the extension of the Calculus of Construction by induction principles does not alter the set of functions in its computational fragment, F ω.
Abstract: We define the notion of an inductively defined type in the Calculus of Constructions and show how inductively defined types can be represented by closed types. We show that all primitive recursive functionals over these inductively defined types are also representable. This generalizes work by Bohm & Berarducci on synthesis of functions on term algebras in the second-order polymorphic λ-calculus (F 2). We give several applications of this generalization, including a representation of F 2-programs in F 3, along with a definition of functions reify, reflect, and eval for F 2 in F 3. We also show how to define induction over inductively defined types and sketch some results that show that the extension of the Calculus of Construction by induction principles does not alter the set of functions in its computational fragment, F ω. This is because a proof by induction can be realized by primitive recursion, which is already definable in F ω.
Journal Article•
TL;DR: A detailed account of the architecture and design decisions of the SOS prototype on UNIX is given, and its ability to map user-defrned semantics (policy decisions) on system-implemented mechanisms is examined.
Abstract: SOS (SOMIW Operating System) is the result of a four-year effort at INRIA to define an object-oriented operating system. SOS provides support for arbitrary, user-defrned, typed objects. The system implements object migration; this mechanism is generic, but can be tailored to specific object semantics thanks to the prerequisite and upcall concepts. SOS also supports Fragmented Objects (FOs), i.e. objects the representation of which spreads across multiple address spaces. Fragments of a single FO are objects that enjoy mutual communication privileges. A fragment acts as a proxy, i.e. a local interface to the FO. All the other mechanisms of SOS are built upon these basic abstractions. Thanks to prerequisites, migration of data may cause the migration and dynamic type-checking and linking of the corresponding code. A distributed object manager, an object storage service, a naming service, as well as a protocol toolbox and some applications, have been built as FOs. This paper gives a detailed account of the architecture and design decisions of the SOS prototype on UNIX. ruy'e examine both good decisions and problems. The basic good decision is our simple object model, and its ability to map user-defrned semantics (policy decisions) on system-implemented mechanisms. The most important problem is the dynamic nature of Fragmented Objects, and inadequate support for them.
05 Jun 1989
TL;DR: The authors suggest nontrivial fixpoint extensions of first-order logic with nondeterministic and/or noninflationary semantics that hold for certain properties of the language FO+IFP.
Abstract: Datalog extensions with fixpoint semantics motivated by database queries and updates are studied. The authors suggest nontrivial fixpoint extensions of first-order logic with nondeterministic and/or noninflationary semantics. Certain properties of the language FO+IFP, such as the collapse of the hierarchy (based on the nesting of fixpoints) or the existential normal form, hold for these various logics. Their expressive power is characterized. >
13 Mar 1989
TL;DR: This work introduces a calculus for concurrent and communicating processes, which is a direct and simple extension of the λ-calculus, and shows that the ε-abstraction is a particular case of reception (on a port named λ), and application is a specific case of cooperation.
Abstract: We introduce a calculus for concurrent and communicating processes, which is a direct and simple extension of the λ-calculus. The communication mechanism we use is that of Milner's calculus CCS: to communicate consists in synchronously sending and receiving a value through a shared port. Then the calculus is parameterized on a given set of port names, which are used in the two primitives for sending and receiving a value — as in the λ-calculus, a value can be any term. We use two parallel constructs: the first is interleaving, which does not allow communication between agents. The second, called cooperation, is a synchronizing construct which forces two agents to communicate on every port name. We show that the λ-calculus is a simple sub-calculus of ours: λ-abstraction is a particular case of reception (on a port named λ), and application is a particular case of cooperation.
01 Jan 1989
TL;DR: A language for databases with sets, tuples, lists, object identity and structural inheritance, which is logic-based with a fixpoint semantics and the introduction of explicit control is proposed.
Abstract: A language for databases with sets, tuples, lists, object identity and structural inheritance is proposed. The core language is logic-based with a fixpoint semantics. Methods with overloading and methods evaluated externally providing extensibility of the language are considered. Other important issues such as updates and the introduction of explicit control are discussed.
01 Feb 1989
TL;DR: The intoduce a calculus called MEIJE built on a monoid of synchronized actions and illustrate some general semantic notions and the concept of subcalculus is illustrated through the description in the language of the class of rational parallel place machines.
Abstract: We gathered here some notes on Milner’s calculi of processes We interpret the terms of these calculi as transition systems We intoduce a calculus called MEIJE built on a monoid of synchronized actions and illustrate some general semantic notions:
we show the equivalence of this calculus with some others
we give an implementation in a calculus restricted to purely atomic actions
we show the universality of MEIJE with respect to the notion of effective transition system and sketch its expressive power with regard to synchronization operators
Finally the concept of subcalculus is illustrated through the description in our language of the class of rational parallel place machines
TL;DR: The multidatabase language msql is described, designed for the manipulation of data from different relational databases, and is an extension of sql, which has become the standard for relational database systems.
TL;DR: In this article, the authors propose a model of CAD transactions which allows a group of cooperating designers to arrive at a complex design without being forced to wait over a long duration, and also allows the group of designers to collaborate on a design with another group by assigning subtasks.
01 Nov 1989
TL;DR: A new equivalence between concurrent processes is proposed, which generalizes the well-known bisimulation equivalence to take into account the distributed nature of processes and is a noninterleaving semantic theory.
Abstract: A new equivalence between concurrent processes is proposed. It generalizes the well-known bisimulation equivalence to take into account the distributed nature of processes. The result is a noninterleaving semantic theory; concurrent processes are differentiated from processes that are non-deterministic but sequential. The new equivalence, together with its observational version, is investigated for a subset of the language CCS, and various algebraic characterizations are obtained.
Book•
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01 Apr 1989
Patent•
15 Mar 1989TL;DR: In this article, an articulated device includes two plates (PI, PS) interconnected by six k members (OLij) disposed in a closed latticework structure, and a control assembly for controlling the relative positions of these two plates.
Abstract: An articulated device includes two plates (PI, PS) interconnected by six k members (OLij) disposed in a closed latticework structure, and a control assembly for controlling the relative positions of these two plates. Each link member is of substantially constant length and the control assembly also includes six slider members (OCij) respectively connected to the six link members (OLij) and to the bottom plate (PI), each slider member being suitable for sliding relative to the bottom plate (PI) along a predetermined sliding direction under drive from a motor (MOTij, TFij).
01 Jan 1989
TL;DR: In this paper, the authors discuss the necessary concepts and the basic properties and some examples of practical problems motivating the use of nonsmooth optimization, and also discuss some possibilities that can be used when a special structure exists in the non-smooth problem.
Abstract: Publisher Summary This chapter discusses the nondifferentiable optimization (NDO). Nondifferentiable optimization or nonsmooth optimization (NSO) deals with the situations in operations research where a function that fails to have derivatives for some values of the variables has to be optimized. For this situation, new tools are required to replace standard differential calculus, and these new tools come from convex analysis. Functions with discontinuous derivatives are frequent in operations research. Sometimes they arise when modeling the problem, sometimes they are introduced artificially during the solution procedure. The chapter discusses the necessary concepts and the basic properties and some examples of practical problems motivating the use of NSO. It is shown how and why classical methods fail. The chapter also discusses some possibilities that can be used when a special structure exists in the nonsmooth problem. It also presents subgradient methods and more recent methods and also covers some orientations for future research.