Showing papers on "Formal language published in 2000"

Role-based authorization constraints specification

Abstract: Constraints are an important aspect of role-based access control (RBAC) and are often regarded as one of the principal motivations behind RBAC. Although the importance of contraints in RBAC has been recogni zed for a long time, they have not recieved much attention. In this article, we introduce an intuitive formal language for specifying role-based authorization constraints named RCL 2000 including its basic elements, syntax, and semantics. We give soundness and completeness proofs for RCL 2000 relative to a restricted form of first-order predicate logic. Also, we show how previously identified role-based authorization constraints such as separtation of duty (SOD) can be expressed in our language. Moreover, we show there are other significant SOD properties that have not been previously identified in the literature. Our work shows that there are many alternate formulations of even the simplest SOD properties, with varying degree of flexibility and assurance. Our language provides us a rigorous foundation for systematic study of role-based authorization constraints.

Dynamic Syntax: The Flow of Language Understanding

Abstract: 1.Towards a Syntactic Model of Interpretation. Natural Language as a Formal Language?. Underspecification in Language Processing. The Representational Theory of Mind. Pronominal Anaphora: Semantic Problems. The Problem of Multiple Ambiguity. The Problem of Uniqueness. The Problem of Indirect Reference. Quantification. Syntactic Processes of Anaphora. The Anaphora Solution ---- Towards a Representational Account. 2. The General Framework. A Preliminary Sketch. The Data Structures of the Parsing Model. Atomic Formulae. Tree Modalities. Basic Tree Structures. Partial Tree Structures. Requirements. Descriptions of Tree Structures. 3. The Dynamics of Tree Building. The Parsing Process -- A Sketch. A Basic Example. A Left--Dislocation Example. Verb--final Languages and the Grammar--parser Problem. The Parsing Process Defined. Computational Rules. Lexical Transitions. Pragmatic Actions and Lexical Constraints. Summary. 4. Linked Tree Structures. Relative Clauses ---- Preliminaries. The LINK Relation. The Data Reviewed. The Analysis ---- A Sketch for English. Defining Linked Tree Structures. Relativisers Annotating Unfixed Nodes. Relatives: Towards a Dynamic Typology. Relativisers Projecting a Requirement. Variation in Locality. Topic Structures and Relatives. Variation in Order ---- Head--Final Relatives. Head--internal Relatives. The Potential for Lexical Variation. Genitive Constructions as LINK Structures. Summary. 5. Wh Questions: A General Perspective. Introduction. The Semantic Diversity of wh Questions. Scopal Properties of wh Expressions. Wh--initial vs wh--in--situ Structures. Wh--in--situ Structures. Wh--in--situ from a Dynamic Perspective. Expletive wh Structures. Partial Movement. Partial Movement as a Reflex of a Requirement. Wh Expressions and Scope Effects. 6. Crossover Phenomena. Crossover ---- The Problem. Crossover ---- The Dynamic Account. Crossover in Relatives. Crossover Phenomena in Questions. Summary. 7. Quantification Preliminaries. Introduction. Scope Effects and Indefinites. Quantification. Quantified NPs. Scope. Term Reconstructions. Applications ---- E--type Anaphora. 8. Reflections on Language Design. The Overall Perspective. Underspecification and the Formal Language Metaphor. English is not a Formal Language. Wellformedness and Availability of Interpretations. Universals and Language Variation. On Knowledge of Language. 9. Appendix: The Formal Framework. Introduction. Declarative Structure. Feature Decorated Tree Construction. Goal--directedness. The Structure of Goal--directed Pointed Partial Tree Models. Tree Descriptions. Procedural Structure. Actions over Goal--directed Partial Tree Models. Natural Languages. Axioms. Finite Binary trees. Partial Trees. Requirements. Actions. Partial Order. Logical Forms. Computational Rules. Update Actions. Pragmatic Actions. General Index. Symbol Index.

ASN.1 Communication Between Heterogeneous Systems

Abstract: I Introduction and History of the Notation 1 Prologue 2 Utilitarian Introduction to ASN.1 3 ASN.1 and the OSI Reference Model 4 Your First Steps with ASN.1 5 Basics of ASN.1 6 History 7 Protocols Specified in ASN.1 II User's Guide and Reference Manual 8 Introduction to the Reference Manual 9 Modules and Assignments 10 Basic Types 11 Character String Types 12 Constructed Types, Tagging, Extensibility Rules 13 Subtype Constraints 14 Presentation Context Switching Types 15 Information Object Classes, Objects, and Object Sets 16 Enough To Read Macros 17 Parameterization III Encoding Rules and Transfer Syntaxes 18 Basic Encoding Rules (BER) 19 Canonical and Distinguished Encoding Rules (CER and DER) 20 Packed Encoding Rules (PER) 21 Other Encoding Rules IV ASN.1 Applications 22 Tools 23 ASN.1 and the Formal Languages SDL, TTCN, GDMO 24 Other Abstract Syntax Notations 25 Epilogue V Appendices A Encoding/Decoding Simulations B Combined Use of ASN.1 and SDL

Automata and Languages: Theory and Applications

Abstract: I Introduction.- Mathematical Background.- 1 Languages.- 2 Automata.- II Regular Languages.- 3 Models for Regular Languages.- 4 Properties of Regular Languages.- III Context-Free Languages.- 5 Models for Context-Free Languages.- 6 Properties of Context-Free Languages.- 7 Special Types of Context-Free Languages and Their Models.- IV Beyond Context-Free Languages.- 8 Generalized Models.- V Translations.- 9 Finite and Pushdown Transducers.- 10 Turing Transducers.- Indices.- Index to Special Symbols.- Index to Decision Problems.- Index to Algorithms.

Teaching and Learning a New Algebra with Understanding.

Abstract: This paper suggests a route to deep, long-term algebra reform that begins not with more new approaches but with elementary school teachers and the reform efforts that currently exist. This route involves generalization and expression of that generality using increasingly formal languages, beginning with arithmetic, modeling situations, geometry, and virtually all mathematics that can or should appear in the elementary grades. This route involves infusing algebra throughout the mathematics curriculum from the very beginning. A model of this approach, suggestions, and examples are provided. (Contains 10 references.) (CCM) Reproductions supplied by EDRS are the best that can be made from the original document.

A Formal Mapping between UML Models and Object-Z Specifications

Abstract: This paper presents a precise and descriptive semantics for core modeling concepts in Object-Z and a formal description for UML class constructs. Given the formal descriptions, it also provides a formal semantic mapping between the two languages at the meta-level, which makes our translation more systematic. Any verification of UML models can take place on their corresponding Object-Z specifications using reasoning techniques provided for Object-Z. With this approach, we provide not only a precise semantic basis for UML but also a sound mechanism for reasoning about UML models.

A Process Compensation Language

Abstract: This paper presents a formal language for the design of component-based enterprise system. The language (StAC) allows the usual parallel and sequential behaviours, but most significant is the concept of compensation that allows a previous action to be undone. The semantics of the language is given by an operational approach. The specification of a system is composed by a set of StAC processes that describe the behaviour of the system and a set of B operations that describe basic computations. Operational semantics is used to justified the integration of StAC processes with B operations.

An Overview of RoZ: A Tool for Integrating UML and Z Specifications

Abstract: This paper presents an approach and a tool to increase specification quality by using a combination of UML and formal languages Our approach is based on the expression of the UML class diagram and its annotations into a Z formal specification Our tool called RoZ supports this approach by making the transition between the UML world and the Z world : from an annotated class diagram, it automatically generates a complete Z specification, the specifications of some elementary operations and some proof obligations to validate the model constraints

Linguistic Geometry: From Search to Construction

Abstract: 1. Introduction. 2. Hierarchy of Formal Languages. 3. Robot Combat for 2D District. 4. Expanding to 3D Space. 5. Deeper Search, More Agents. 6. Concurrency, nxn District. 7. Scheduling: Artificial Conflict. 8. Generating Techniques. 9. Language of Trajectories. 10. Language of Zones. 11. Translations. 12. Languages of Searches. 13. From Search to Construction. 14. Computational Complexity. Future Challenges. References. Index.

Effective control synthesis for DES under partial observations

Abstract: A procedure is given for the effective solution of an infinite-string supervisory control problem under partial observations, for the case where the plant and specification languages are represented by finite /spl omega/-automata (automata on infinite strings), and the observation mask by a finite Moore automaton. This solves an /spl omega/-language version of the standard centralized supervisory control problem under partial observations. It is shown that a natural extension to decentralized control is undecidable, even if the plant, the specification languages and the masks are represented by finite automata. This undecidability result carries over to the finite-string case.

A formal language for composition

Abstract: A composition language based on a formal semantic foundation will facilitate precise specication of glue abstractions and compositions, and will support reasoning about their behaviour. The semantic foundation, however, must address a set of requirements like encapsulation, objects as processes, components as abstractions, plug compatibility, a formal object model, and scalability. In this work, we propose the L-calculus, an extension of the -calculus, as a formal foundation for software composition, dene a language in terms of it, and illustrate how this language can be used to plug components together.

A semantic feature language for sculptured object modelling

Abstract: Feature technology is a promising approach for modelling an object since it provides a systematic representation scheme for the object semantics in various engineering application domains. A semantic oriented feature language is proposed in this paper to cover the modelling of the sculptured object class. The language consists of two components: vocabularies and grammar. Features and feature relationships are vocabularies of the language manipulated by the grammar. Although geometry is the main characteristic that differentiates the sculptured object from the regular shaped object, it is just a set of auxiliary information in the feature vocabulary class. The relationships between various features within a sculptured object reflecting its functionality are the major concerns. Parametric modelling of sculptured objects is also discussed in the feature language.

Automatic Programming of Morphological Machines by PAC Learning

Abstract: An important aspect of mathematical morphology is the description of complete lattice operators by a formal language, the Morphological Language (ML), whose vocabulary is composed of infimum, supremum, dilations, erosions, anti-dilations and anti-erosions This language is complete (ie, it can represent any complete lattice operator) and expressive (ie, many useful operators can be represented as phrases with relatively few words) Since the sixties special machines, the Morphological Machines (MMachs), have been built to implement the ML restricted to the lattices of binary and gray-scale images However, designing useful MMach programs is not an elementary task Recently, much research effort has been addressed to automate the programming of MMachs The goal of the different approaches for this problem is to find suitable knowledge representation formalisms to describe transformations over geometric structures and to translate them automatically into MMach programs by computational systems We present here the central ideas of an approach based on the representation of transformations by collections of observed-ideal pairs of images and the estimation of suitable operators from these data In this approach, the estimation of operators is based on statistical optimization or, equivalently, on a branch of Machine Learning Theory known as PAC Learning These operators are generated as standard form morphological operators that may be simplified (ie, transformed into equivalent morphological operators that use fewer vocabulary words) by syntactical transformations

Towards the principled design of software engineering diagrams

Abstract: Diagrammatic specification, modelling and programming languages are increasingly prevalent in software engineering and, it is often claimed, provide natural representations which permit of intuitive reasoning. A desirable goal of software engineering is the rigorous justification of such reasoning, yet many formal accounts of diagrammatic languages confuse or destroy any natural reading of the diagrams. Hence they cannot be said to be intuitive. The answer, we feel, is to examine seriously the meaning and accuracy of the terms “natural” and “intuitive” in this context. This paper highlights, and illustrates by means of examples taken from industrial practice, an ongoing research theme of the authors. We take a deeper and more cognitively informed consideration of diagrams which leads us to a more natural formal underpinning that permits (i) the formal justification of informal intuitive arguments, without placing the onus of formality upon the engineer constructing the argument; and (ii) a principled approach to the identification of intuitive (and counter-intuitive) features of diagrammatic languages.

Expressivity in Polygonal, Plane Mereotopology

Abstract: In recent years, there has been renewed interest in the development of formal languages for describing mereological (part-whole) and topological relationships between objects in space. Typically, the non-logical primitives of these languages are properties and relations such as ‘ x is connected’ or ‘ x is a part of y ’, and the entities over which their variables range are, accordingly, not points , but regions : spatial entities other than regions are admitted, if at all, only as logical constructs of regions. This paper considers two first-order mereotopological languages, and investigates their expressive power. It turns out that these languages, notwithstanding the simplicity of their primitives, are surprisingly expressive. In particular, it is shown that infinitary versions of these languages are adequate to express (in a sense made precise below) all topological relations over the domain of polygons in the closed plane.

A theory-based representation for object-oriented domain models

Abstract: Formal software specification has long been touted as a way to increase the quality and reliability of software; however, it remains an intricate, manually intensive activity. An alternative to using formal specifications directly is to translate graphically based, semiformal specifications into formal specifications. However, before this translation can take place, a formal definition of basic object oriented concepts must be found. The paper presents an algebraic model of object orientation that defines how object oriented concepts can be represented algebraically using an object oriented algebraic specification language O-SLANG. O-SLANG combines basic algebraic specification constructs with category theory operations to capture internal object class structure, as well as relationships between classes.

Teaching Formal Languages by an Intelligent Tutoring System.

Abstract: For separating waste from a fiber-and-waste mixture in a textile machine, the mixture is tangentially thrown from a rotating roll by centrifugal force. An air flow is directed onto the traveling particles of the mixture such that fibers are returned to the roll, while the waste particles are allowed to continue their travel. Subsequently, the waste particles are removed by suction.

Reliable hardware support for the use of formal languages in high assurance systems

Abstract: A dataflow processor comprising a combiner for combining instructions and data, processing elements for carrying out the instructions, has error checking at the inputs to the processing elements and the combiner, and has self-checking circuitry for these parts. The amount of circuitry which needs to be trusted, (i.e. of proven design, and verified operation) can be advantageously limited. This enables the processor to be constructed more simply and to operate faster. The processing elements may have a series of state machines, each checking the output of the previous. Self checking circuitry may be constructed using combinations of basic configurable verified circuit. This circuit has a reversible Boolean function, and other circuitry to check its output. The other circuitry has a second reversible Boolean function for regenerating the original inputs, and a comparator for verifying if the regenerated values match the original values.

On the Definition of Word Hyperbolic Groups

Abstract: Formal languages based on the multiplication tables of finitely generated groups are investigated and used to give a linguistic characterization of word hyperbolic groups.

Formally modeling UML and its evolution: a holistic approach

Abstract: Due to the pervasiveness of diagrams in human communication and because of the increasing availability of graphical notations in Software Engineering, the study of diagrammatic notations is at the forefront of many research efforts. The expressive power of these kinds of languages and notations can be remarkably improved by adding extensibility mechanisms Extensibility, the ability of a notation or a modeling language to be extended from its own modeling constructs, is a feature that has assumed considerable importance with the appearance of the UML (Unified Modeling Language). In this paper, a holistic proposal to formally support the evolution of the UML metamodel is presented. To attain this aim, an algebraic formalization is provided which leads to a seamless formal model of the UML four-layer semantics architecture. These two characteristics — being holistic and seamless together with reflection are the most innovative aspects of the research with respect to formalizing the UML. In particular, a central role is played by reflection. A formal language supporting this feature called Maude is studied and put forward as the basis for the formalization of the UML extensibility mechanisms. Since Maude is an executable specification language, the final set of formal models can also be used as a UML virtual machine at the specification level. To illustrate the approach, a UML Class Diagram prototype is implemented using the Maude interpreter. The integration of this Maude prototype with a UML commercial CASE has been developed, in Java, and is currently working.

On the Power of Tree-Walking Automata

Abstract: Tree-walking automata (TWAs) recently received new attention in the fields of formal languages and databases. Towards a better understanding of their expressiveness, we characterize them in terms of transitive closure logic formulas in normal form. It is conjectured by Engelfriet and Hoogeboom that TWAs cannot define all regular tree languages, or equivalently, all of monadic second-order logic. We prove this conjecture for a restricted, but powerful, class of TWAs. In particular, we show that 1-bounded TWAs, that is TWAs that are only allowed to traverse every edge of the input tree at most once in every direction, cannot define all regular languages. We then extend this result to a class of TWAs that can simulate first-order logic (FO) and is capable of expressing properties not definable in FO extended with regular path expressions; the latter logic being a valid abstraction of current query languages for XML and semi-structured data.