A familial specification language for database application systems

The Familial Specification Language is a set theoretic and functional language providing a unified approach to the less-procedural design of database application systems. The language is proposed to be both a database language and an application program specification language. The unique data structure employed, the family of sets, provides the designer with a unified framework, both to model and maintain data, and to algebraically specify the application programs without looping or branching, and with no side effects. Using the same data structure in both the data model and the problem specification creates a natural interface between the database and the application programs. Special emphasis is placed on aggregation and classification, the major problems is business data processing.     

Files in an interactive environment

A well designed file system can significantly simplify the design of and increase the reliability of interactive programs. A summary of the specifications of a convenient file system that is substantially independent of the host operating system and some experiences using the system are described.     

Eventor: an authoring system for interactive multimedia applications

Programming, testing, and maintaining interactive multimedia applications (IMAs) are still difficult and expensive, while substantial progress has been made to reduce the burden on authors. As IMAs get larger and more complex the difficulties will increase. To overcome the complexity of such IMAs, we argue that authoring systems should provide such facilities as (1) a traditional and intuitivedivide-and-conquer paradigm for solving large and complex problems in various fields, (2)formal specification of the behaviors of IMAs for checking the syntactic correctness of visual expressions or semantic anomalies, and (3)automatic aids like validation of temporal constraints and verification of visual expressions. In this paper, we investigate the properties of IMAs for recognizing the inherent interactivity and concurrency. We propose a specification method based on Milner'sCalculus of Communicating Systems (CCS), which is a well-known formal mechanism for specifying the concurrency in various distributed applications. We also design and implement an authoring system calledEventor (Event Editor), which is based on CCS and composed of three tools: a Temporal Synchronizer, a Spatial Synchronizer, and a User Interaction Builder. They focus on describing the temporal and spatial synchronizations and user interactions while they rely on existing tools in Intel's Digital Video Interactive (DVI) for supporting other functionalities. By editing a simple computer aided instruction (CAI) application, we illustrate that our specification mechanism is well-suited for handling the interactivity of multimedia applications, and Eventor is a simple, efficient, and powerful enough tool to handle practical applications. Especially the incremental refinement and the formal specification based on the CCS allow Eventor to be extended with formal verifications to cope with large and complex applications.     

Critique of the Lake Arrowhead Three

The photograph and autobiography of Dr. Leslie Lamport were published in Volume 4, Issue No. 2, 1990 on page 59     

Design and implementation of an interactive test bed

An interactive test bed for programs written in the system development language CLSD is described. It consists of a compiler and an interactive interpreter. The test facilities and the internal design of the test and bed are described in detail. Experience has demonstrated this to be a very valuable tool in program development.     

EDIT—an interactive network service; design and implementation

EDIT is a time-sharing system which offers interactive services over the NPL network. These services include various kinds of editing, word processing, data movement and file control. The system is implemented on a PDP11/40 and can serve up to 30 users simultaneously, on high-speed displays and other terminals. There is an attached background processor (PDP11/45) which supports graphics and background jobs. This paper describes the design and implementation of EDIT and relates this to the needs of the system and of its users.     

Algebraic query optimisation for database programming languages

A major challenge still facing the designers and implementors of database programming languages (DBPLs) is that of query optimisation. We investigate algebraic query optimisation techniques for DBPLs in the context of a purely declarative functional language that supports sets as first-class objects. Since the language is computationally complete issues such as non-termination of expressions and construction of infinite data structures can be investigated, whilst its declarative nature allows the issue of side effects to be avoided and a richer set of equivalences to be developed. The language has a well-defined semantics which permits us to reason formally about the properties of expressions, such as their equivalence with other expressions and their termination. The support of a set bulk data type enables much prior work on the optimisation of relational languages to be utilised. In the paper we first give the syntax of our archetypal DBPL and briefly discuss its semantics. We then define a small but powerful algebra of operators over the set data type, provide some key equivalences for expressions in these operators, and list transformation principles for optimising expressions. Along the way, we identify some caveats to well-known equivalences for non-deductive database languages. We next extend our language with two higher level constructs commonly found in functional DBPLs: set comprehensions and functions with known inverses. Some key equivalences for these constructs are provided, as are transformation principles for expressions in them. Finally, we investigate extending our equivalences for the set operators to the analogous operators over bags. Although developed and formally proved in the context of a functional language, our findings are directly applicable to other DBPLs of similar expressiveness. Edited by Matthias Jarke, Jorge Bocca, Carlo Zaniolo. Received September 15, 1994 / Accepted September 1, 1995     

Modelling and validating the man-machine interface

This paper describes a formal model for expressing the functional requirements of the man-machine interfaces of interactive systems. It also shows how this model can facilitate the automation of other useful activities such as checking for inconsistency, redundancy, and incompleteness in the specification, and validating the implementation of the interface against its original requirements. Finally, the paper comments on the authors' experience in developing an interactive system using this formal model.     

Modularising the specification of a small database system in extended ML

A case study in the modular specification and refinement of a small database system is presented in Extended ML. Two similar requirements specifications are given and a program development step from each these is presented. The structure resulting from the first program development step is similar to that given in [FiJ90] and is presented as an answer to the challenge problem given in that paper, while the second development step is presented as a possible alternative which is more suited to the Extended ML style of program development. In the context of these two development steps the module facilities of Extended ML, their role in specification and program development and their ability to meet the challenge of [FiJ90] are examined.This research was supported by SERC grant GR/E 78463     

Verifying of interface assertions for infinite state Mealy machines

This paper aims at techniques and methods for the verification of logical assertions about the interface behavior of generalized I/O-state machines. The interface behavior of such machines is specified by interface assertions formulated in predicate logic. Interface assertions specify the interface behavior of state machines in terms of the streams of messages produced via their input and output channels. The verification of interface assertions for state machines is carried out with the help of generalized invariants. Such invariants are proved for state machines in terms of stable assertions. Nontrivial liveness properties such as fairness lead to specifications and also to state machines defining sets of computations that specify sets of output streams that are not limit closed. Elementary examples for such cases are described and the implied complications are analyzed. Furthermore, verification methods are provided for these cases and demonstrated by small examples.     

Information systems in modeling interactive computations on granules

In this paper, we discuss the importance of information systems in modeling interactive computations performed on (complex) granules and we propose a formal approach to interactive computations based on generalized information systems and rough sets which can be combined with other soft computing paradigms such as fuzzy sets or evolutionary computing, but also with machine learning and data mining techniques. Information systems are treated as dynamic granules used for representing the results of the interaction of attributes with the environment. Two kinds of attributes are distinguished, namely, the perception attributes, including sensory attributes, and the action attributes. Sensory attributes are the basic perception attributes, other perception attributes are constructed on the basis of the sensory ones. Actions are activated when their guards, being often complex and vague concepts, are satisfied to a satisfactory degree. The guards can be approximated on the basis of measurements performed by sensory attributes rather than defined exactly. Satisfiability degrees for guards are results of reasoning called the adaptive judgment. The approximations are induced using hierarchical modeling. We show that information systems can be used for modeling more advanced forms of interactions in hierarchical modeling. The role of hierarchical interactions is emphasized in the modeling of interactive computations. Some illustrative examples of interactions used in the ACT-R 6.0 system are reported. ACT-R 6.0 is based on a cognitive architecture and can be treated as an example of a highly interactive complex granule which can be involved in hierarchical interactions. For modeling of interactive computations, we propose much more general information systems than the studied dynamic information systems (see, e.g., Ciucci (2010) [8] and Pa?asiński and Pancerz (2010) [32]). For example, the dynamic information systems are making it possible to consider incremental changes in information systems. However, they do not contain the perception and action attributes necessary for modeling interactive computations, in particular for modeling intrastep interactions.     

Consistent specification of interface suites in UML

The paper motivates and describes a model oriented approach for consistent specification of interface suites in UML. An interface suite is a coherent collection of interfaces defining interactions that transcend component boundaries. The specification of interface suites contains diagrammatic views and documentation, but it is extended with templates for structured specifications deriving from the ISpec approach. To guarantee that the specification views, documentation and templates are consistent, a specification model has been constructed. The model contains both structural and behavioural information, represented in the form of sequences of carefully designed tuples. The model provides the underlying structure for the tool supporting the design process. The tool directs the designer to specify all elements of the model in a consistent way. The specification is collected both by customized specification templates and by diagrams. The documentation and the diagram elements – both derived from the template information – are automatically generated. This prevents errors and provides specification consistency. Initial submission: 15 February 2002 / Revised submission: 20 September 2002 Published online: 2 December 2002 RID="*" ID="*"Supported by PROGRESS grant EES.5141 and ITEA DESS grant IT990211.     

A graphical database interface

A graphical database interface suitable for casual, naive users is described. It provides the user with a logical model of the database; this model typically being an abstraction of the actual database structure, and with an easy means of specifying a query through the use of a pointing device. The interface is a front-end processor and is logically separate from the database management system, it is thus possible to use it with any system.     

A visual shell interface to a database

This paper describes a visual command language for a workstation with a bit-mapped display and a mouse that can be used to create different user interfaces. Primitive interface components can be combined into more complex user interfaces. The user specifies interconnections between these components over which data and commands can be sent by pointing with a mouse. Primitive interface components are described for creating several different database user interfaces. The design and implementation of the software architecture is described, including the primitives for database interfaces and the communication protocols used by the system.     

Investigation of multidimensional data using the interactive pattern analysis system ispahan

In 1972, Kanal has enumerated some reasons for the desirability of interactive pattern analysis and classification systems (IPACS). One such system, ISPAHAN, was developed at the Department of Medical Informatics of the Free University in Amsterdam. Although this system is still expanding, it is now in operation. In order to obtain some experience with its properties three data sets, varying in complexity were analysed. Especially the possibility of applying various pattern recognition techniques in succession is shown to lead to an unsupervised classification scheme which may yield essentially the same results as the maximum likelihood decision rule applied to the labelled data set. The results of unsupervised methods are generally influenced by user chosen initial conditions. An objective criterion should therefore be used to compare different configurations. The use of one such criterion, measuring the compactness of the resulting clusters, is demonstrated in this paper.     

An interpreter for LOTOS,a specification language for distributed systems

LOTOS is an executable specification language for distributed systems currently being standardized within ISO as a tool for the formal specification of open systems interconnection protocols and services. It is based on an extended version of Milner's calculus of communicating systems (CCS) and on ACT ONE abstract data type (ADT) formalism. A brief introduction to LOTOS is given, along with a discussion of LOTOS operational semantics, and of the executability of LOTOS specifications. Further, an account of a prototype LOTOS interpreter is given, which includes an interactive system that allows the user to direct the execution of a specification (for example, for testing purposes). The interpreter was implemented in YACC/LEX, C and Prolog. The following topics are discussed: syntax and static semantics analysis; translation from LOTOS external format to internal representation; evaluation of ADT value expressions and extended CCS behaviour expressions. It is shown that the interpreter can be used in a variety of ways: to recognize whether a given sequence of interactions is allowed by the specification; to generate randomly chosen sequences of interactions; in a user-guided generation mode, etc.     

DUET — A database user interface design environment

The DUET database user interface management system aims to help database application programmers to create, modify, and maintain interactive graphical user interfaces for different applications. DUET supports the creation of a complete user interface via direct manipulation techniques. It provides a large set of database widgets which are necessary for database applications. DUET provides facilities to step through the validation of a created user interface. A user interface can be saved as C code which can be integrated into a database backend. In this paper, the features and the architecture of DUET are presented.     

An operating system for interactive terminals

Conventional operating systems have for many-years used the ideas of standard stream interfaces to peripherals. Multi-tasking has been used in order to give an efficient response while maintaining simplicity and flexibility for the user. This paper describes an extension to an operating system which makes similar facilities available for the control of interactive workstations, and also provides a command dispatcher which enables the straightforward implementation of arbitrary user-defined command languages. The current system has been written in BCPL to run on a PDP 11/45 handling a Vector General display, but the design is suitable for use with a variety of terminals, computers and languages.