Monografias em Ciência da Computação
1994
ABSTRACTS
Departmento de Informática
Pontifícia Universidade Católica do Rio de Janeiro - PUC-Rio
Rio de Janeiro - Brazil
This file contains a list of the technical reports of the Departmento de Informática,
Pontifícia Universidade Católica do Janeiro - PUC-Rio, Brazil,
which are published in our series Monografias em Ciência da Computação (ISSN
0103-9741), edited by Prof. Carlos Lucena. Please note that the reports not
available for download are available in their print format and can be obtained
via the e-mail below.
For any questions, requests or suggestions, please contact:
Rosane Castilho
bib-di@inf.puc-rio.br
Last update: 18/DECEMBER/2003
[MCC01/94]
VELOSO, P.A.S. On fork algebras and reasoning about programs. 16 p.
Eng. E-mail: bib-di@inf.puc-rio.br
Abstract: Fork algebras provide a useful basis for relational
reasoning about programs and specifications. They arise as extensions
of relational algebras with a new operator, called fork, which anables
the introduction, by definition, of projections. In this paper we
examine some fundamental issues concerning fork algebras, presenting
the profs of expressiveness and representability and discuss their
importance for reasonig about programs.
[MCC02/94]
ANDREATTA, A.A.; Ribeiro, C.C. A graph partitioning heuristic for the
parallel pseudo-exhaustive logical test of VLSI combinational circuits.
37 p. Eng. E-mail: celso@inf.puc-rio.br
Abstract: The logical test of integrated VLSI circuits is one of the
main phases of their design and fabrication. The pseudo-exhaustive
approach for the logical test of integrated circuits consists in
partitioning the original circuit to be tested into non-overlapping
subcircuits with a small, bounded number of subcircuits, which are
then exhaustively tested in parallel. In this work we present an
approximate algorithm for the problem of partitioning integrated
combinational circuits, based onthe tabu search metaheuristic. The
proposed algorithm presents several original features, such as: the
use of a reduced neighborhood, obtained from moves involving only a
subset of boundary nodes; complex moves which entail several resulting
moves, although the variations in the cost function arevery easily
computable; a bi-criteria cost function combining the number of
subcircuits and the number of cuts, which simultaneously adds
adiversification strategy to the search; and the use of a bin-packing heuristic as a
post-optimization step. The behavior of the
proposed algorithm was evaluated through its application to a set of
benchmark ISCAS combinational circuits. The computational results have
been compared withthose obtained by other algorithms in the literature,
with significant improvements. The average reduction rates have been of
the order of 30% inthe number of subcircuits in the partition, and of
the order of 40% in the number of cuts.
[MCC
03/94]
IERUSALIMSCHY, R.; FIGUEIREDO, L.H.; CELES FILHO, W. Reference manual of
the programming language Lua. 21 p. Eng. E-mail: roberto@inf.puc-rio.br
Abstract: Lua is an embedded programming language designed to be
used as a configuration language for any program that needs one. This
document describesthe Lua programming language and the API that allows
interaction between Lua program and its host C program. It also presents
some examples of using the main features of the system.
[MCC04/94]
de SOUZA, C.S.; JAMES, D. Especificações formais para linguagens visuais
de programação. 11 p. Eng. E-mail: clarisse@inf.puc-rio.br
Abstract: In this work we present LvPASCAL, a visual programming
language based on PASCAL. After a short survey of concepts usually
associated to visualprogramming, we propose that the advent of real
instances of such type of graphical code claims for syntactical
formalization and cognitive motivation. Syntactic formalization is
needed for program compilation and,in LvPASCAL, such formalization is
done with L-Systems. Cognitive motivation is needed for a programmer to
be able to write and understand code in the language. In LvPASCAL, the
motivation for imaging is driven towards perception, in an association
between geometric forms and control and modularization abstractions.
[MCC05/94]
de SOUZA, C.S.; GARCIA, A.C.B. Towards a rethoric of active design
documents. 13 p. Eng. E-mail: clarisse@inf.puc-rio.br
Abstract: Design documentation is costly, often inconsistent, and
generally incomplete. Active Documents offer an active approach to
capturingand delivering design rationale. In ADD, an existing
implementation of anactive document, what is stored and manipulated by
system and user is notjust information, but knowledge. Delivering
knowledge at the interface level is a complex task, involving
communicative strategies that fully explore documentation resources and
adequately meet users cognitive needs. The implemented system
generates information that can be displayed as an explanation, but
it lacks rhetorical organization and structuring. Users, on their own,
cannot be expected to (1) explore the full wealth of knowledge
resources available in an active document, and (2) diagnose their own
misconceptions about the design model and history. This paper discusses
the potential for improving the input and output code, as well as for
introducing dialogue structure, so that the knowledge usability
problem in (1) and the cognitive paradox problem in (2) are made
smaller.
[MCC06/94]
SOUZA, C.S. Structure and expresiveness visual computer languages. 18 p.
Eng. E-mail: clarisse@inf.puc-rio.br
Abstract: One of the meanings that can be assigned to the expression
Visual Programming Language (VPL) is that of a programming language
whose tokens are visual, rather than textual. Despiste the linguistic
parallel, however, VPL's can hardly challenge their textual
counterparts in the construction of even very simple software programs.
But Visual Command Languages (VCL's) seem to have nearly overtaken
their textual counterparts as a protocol for user-system interaction.
Thus, the very nature of software programs and interface commands
appear to be differentially suited for visual representation. In this
paper, a classification of visual languages is proposed with respect to
the dimensions of structural complexity and interactivity. Whereas
languages deprived of a cognitively clear conceptual model in the
semantic component seem to be necessarily low on the interactive side,
languages deprived of formally clear structuring rules in the
syntactic component do not. But, the lack of a powerful grammar seems
to affect the language's ability to represent adequately the elements
involved in even the simplest computer processes. In order to integrate
the adequacy of VCL's to a programming environment, an end-user VPL
schema is presented, in which visual parametric and syntactic
variations of a classical fractal image - the Koch Curve - are assigned
perceptually motivated procedural meanings. Although images in this VPL
schema are abstract, and not semiotically iconic or indexical as the
majority of VCL images, underlying structural regularities seem to
accommodate consistenly some semantic notions related to data, control
and modular abstractions. A global linguistic and semiotic analysis of
the proposed VPL schema suggests that there may be important expressive
limits to the quality of genuinely visual programming languages.
Nevertheless, the limits of successful visual command languages may
apparently be extended to incorporate abstractions that are desirable
for end-user programming applications.
[MCC07/94]
FUKS, H.; MOURA, L.M. A document based approach for cooperation. 21 p.
Eng. E-mail: hugo@inf.puc-rio.br
Abstract: This article outlines a document based approach for
cooperation. It proposes a cooperation model, wich states the way team
members access the documents of a project. It is the underlying model
for a cooperative system, where developers concentrate on the
application's domain, ignoring the aspects related to the cooperative
process.
[MCC08/94]
GARCIA, A.C.B.; STEFIK, M.J.; HOWARD, H.C. Design rationale for
collaboration: the active document approach. 29 p. Eng. E-mail:
bicharra@inf.puc-rio.br
Abstract: We present a new approach for supporting documentation in
routine design tasks using computationally active documents. This
approach substantially reduces the costs of collaborative design.
The major costs are in the time required to check and maintain
consistency between design decisions and requirements, the time to
explore a large design space, and the time lost in communication
delays between people with different expertise. By reducing these
costs, the active design document approach supports the creation,
use and revision of design documents. We demonstrate the
feasibility of the approach with a detailed case study of its
application to the preliminary design of heating ventilation and
air conditioning (HVAC) systems. Evaluation of a prototype
system confirms that where the approach is applicable, it can
significantly improve the quality and reduce the cost of design
documentation.
[MCC09/94]
GARZA, J.M.; GARCIA, A.C.B.; HOWARD, H.C. Making the case for
design rationale in the A/E/C industry. 12 p. Eng. E-mail:
bicharra@inf.puc-rio.br
Abstact: Articulation and use of design rationale are critical
elements in improving design, construction, and facility management
in the architecture/engineering/construction (A/E/C) industry.
This paper summarizes some of the research work on design
rationale in the fields of construction and software engineering,
and shows how design rationale could be captured and employed
in the A/E/C industry. The articulation of design rationale
should be a standard activity in the entire design process
starting with owner's initial conception of the facility,
the designer's elaborations on that concept, construction by
the contractor, and finally, operation by the facility's managers.
Owners of constructed facilities need to recognize the
usefulness of this new design output product called "design
rationale" as a valuable addition to the typical construction
documents already produced, i.e., drawings, specifications,
and as-builts. We argue that design rationale, if adopted as a
valid concept, can be articulated and used through software
tools and that these need to be embedded within the key
software packages that designers are already using.
[MCC10/94]
GARCIA, A.C.B.; HOWARD, H.C.; STEFIK, M.J. Improving design and
documentation by using partially automated synthesis. 35 p. Eng.
E-mail: bicharra@inf.puc-rio.br
Abstract: One of the products of engineering, besides constructed
artifacts, is design documentation. To understand how design
participants use documentation, we interviewed designers and
typical documentation users and also took protocols of them both
creating and using design documentation. Our protocols were taken from
realistic projects of preliminary design for heating, ventilation
and air conditioning systems (HVAC). Our studies of document
creation and use revealed three important issues: (1) Design
participants not only look up design facts; they frequently
access documents to obtain information about the rationale for
design decisions; (2) The design rationale that they seek is
often missing from the documents; (3) design requirements
change frequently over a project life cycle so that design
documents are often inconsistent and out-of-date. Recognizing
these documentation issues in design practice, we developed
a new approach in which documents are no longer static records,
but rather interactive design models supporting a case. We
demonstrated the feasibility of the approach by constructing
a running system and testing it designers on realistic problems.
We also analyze the costs and benefits of creating and using
documentation of design rationale and of the active documents
approach in praticular for routine, preliminary design in
domains where community practice is widely shared and largely
standardized. The approach depends on the feasibility of creating
a parametric design model for the design domain.
[MCC11/94]
BIGONHA, M.A.S.; RANGEL NETTO, J.L.M. Sistema gerador de geradores
de código para arquiteturas superescalares. 18 p. Port. E-mail:
bib-di@inf.puc-rio.br
Abstract: Modern computer architectures have motivated research for
more efficient compiler techniques. These new architectures, however,
delegate the solution of the most complicated problems in code
generation to the compiler. The focus of this paper is the design
of a retargetable code generator system for superscalar architectures.
We also show the results of the study of several problems related to
code generation to these processors.
[MCC12/94]
BIGONHA, M.A.S.; RANGEL NETTO, J.L.M. Linguagens para descrição de
arquiteturas de computadores. 18 p. Port. E-mail: bib-di@inf.puc-rio.br
Abstract: Modern computer architectures lead to research looking for
better techniques for effective implementation of compilers wich must
be able to produce high-quality code. In the special case of
superscalar architectures we have reduced instructions sets, and
instructions must be combined to warrant efficient execution by the
compilers, which have more complex back-ends than their CISC
counterparts. Objectives of this work are the study of the characteristics of formal languages for the description of
architectures, meant for use with code generator generators and the
project, and the semantic validation of an architecture description
language adequate for use with the generator system.
[MCC13/94]
MAIBAUM, T.S.E.; VELOSO, P.A.S. Logical specifications: 1. Introduction
and overview. 16 p. Eng. E-mail: bib-di@inf.puc-rio.br
Abstract: The logical approach to formal specifications regards
specifications as axiomatic presentations of theories in standard
first-order logic. Its motivations come mainly from two related
sources: concepts aikin to program verification and "liberal"
specifications (which provide flexibility for specifying what one
whishes without forcingover-specification). The rationale for our
standpoint is the realisation that programming has to do with syntactical objects rather with their semantical counterparts and,
thus, that program and specification development consists of the
manipulation of theories. This introductory report is intended to set
the stage and provide a general overview. It presents and discusses
some general ideas underlying our property-oriented approach. We start
by examining the motivations for our approach and then proceed to
consider some of its consequences for stepwise development:
implementations and their composition as well as parametrisation and
instatiation. We also briefly comment on our approach to errors via
liberal specifications. This report is a draft of the first section of
a handbook chapter. Subsequent reports will analyse these
and related points in more detail.
[MCC14/94]
VELOSO, P.A.S.; MERÉ, M.C. Construtores parametrizados de sortes. 10 p.
Port. E-mail: bib-di@inf.puc-rio.br
Abstract: Some sort constructors needed for implementing formal
specifications are presented parameterized specifications.
Implementation of formal specifications are crucial in formal program
development. Specifications are viewed as theory presentations:
theories in many-sorted first-order logic presented by a set of axioms. Implementation of formal specifications can also be described in terms
of simple logical concepts. The constructors examined akin to those
found in programming languages, namely record, discriminated union,
subsorting and quotient. It is of interest to describe, in a formal
way, how new sorts can be constructed from given sorts.
[MCC15/94]
OLIVEIRA, A.P.A.; LEITE, J.C.S.P. SERBAC: uma estratégia para definição
de requisitos. 16 p. Port. E-mail: julio@inf.puc-rio.br
Abstract: No English abstract provided.
[MCC16/94]
GILVAZ, A.P.P.; LEITE, J.C.S.P. FAES - uma estratégia para aquisição
de informações. 19 p. Port. E-mail: julio@inf.puc-rio.br
Abstract:In this article we present FAES, an automated assistant for
interviews, and discuss its use and limitations. Interview is the most
used technique for fact gathering, but suffers from several problems:
tacit knowledge, the say do problem and has to deal with a large
quantity of information. FAES is based on an information system
conceptual model and is designed to help mitigate some of the cited
problems. FAES guides the software engineer in the process of fact
gathering by proposing questions to be asked to clients and providing
an analysis of the client's answers as provided by the software
engineer. The conceptual model was tested in a couple of cases and the
assistant was used in a real case study.
[MCC17/94]
IERUSALIMSCHY, R.; RODRIGUEZ, N.L. Side effect free functions in
object-oriented languages. 20 p. Eng. E-mail: roberto@inf.puc-rio.br
Abstract: This paper presents a method for statically verifying that
functions do not produce side effects, in an object-oriented language.
The described model, although not allowing any changes to pre-existing
objects during a function call, permits an imperative style of
programming, where new objects can be freely created and manipulated.
[MCC18/94]
FIGUEIREDO, L.H.; IERUSALIMSCHY, R.; CELES Fo., W. The design and
implementation of a language for extending applications. 11 p.
Eng. E-mail: roberto@inf.puc-rio.br
Abstract: We describe the design and the implementation of Lua, a
simple, yet powerful, language for extending applications. Although
Lua is a procedural language, it has data description facilities, and
has been extensively used in production for several tasks including
user configuration, general-purpose data-entry, description of user
interfaces, description of application objects, and storage of
structured graphical metafiles.
[MCC19/94]
BORGES, R.; CASSINO, C.; CERQUEIRA, R.; IERUSALIMSCHY, R. UAI -
um framework para suporte a objetos visuais. 10 p. Port. E-mail:
roberto@inf.puc-rio.br
Abstract: UAI is a framework of C++ classes for developing interactive
applications, with support for visual objects. The main features of
UAI are the high integration between the interface and the graphic
systems and its portability. This work describes the facilities of
UAI for modeling active objects. The software is currenly running on
X-Windows, MS-DOS, and MS-Windows.
[MCC20/94]
CELES FILHO, W.; FIGUEIREDO, L.H.; GATTASS. M.; IERUSALIMSCHY, R. Estratégias de
reúso de software no TeCGraf. 9 p. Port. E-mail:
roberto@inf.puc-rio.br
Abstract: No English abstract provided.
[MCC21/94]
COWAN, D.D.; LUCENA, C.J.P. Abstract data views: motivation, current
proposal and research trends. 12 p. Eng. E-mail: lucena@inf.puc-rio.br
Abstract: This paper provides an overview of our current research work
on Abstract Data Views (ADVs). ADVs are a new design concept that
supports reuse-in-the-large and are a method for specifying and
abstracting interfaces between objects. We present the motivation for
the problem, express the requirements for an appropriate solution and
outline our current proposal. We also provide an overview of the
theoretical aspects of ADVs and illustrate how they provide a general
solution for the module interconnection problem in object-oriented
design.
[MCC22/94]
ALENCAR, P.S.C.; CARNEIRO-COFFIN, L.M.F.; COWAN, D.D.; LUCENA, C.J.P.
The semantics of abstract data views: a design concept to support
reuse-in-the-large. 18 p. Eng. E-mail: lucena@inf.puc-rio.br
Abstract: In this paper we present a preliminary formal semantics
of a new design concept to support reuse-in-the-large called Abstract
Data Views (ADVs). This approach toward reuse is described informally
followed by the presentation of a formal basis for its semantics. The
semantics of the relationship of ADVs and ADTs as well as the
semantics of a specification constructor for simple composition are
presented. Issues on reusability, the main concern of the presented
design concept, and the role of instantiation and naming requirements
in this contex are discussed. We also indicate how the dynamic
features of ADVs and consistency requirements can be represented
through a temporal logic formalism. Finally, a proff outline of a
modularization theorem for reuse of ADTs interpreted through ADVs
is presented.
[MCC23/94]
CARNEIRO-COFFIN, L.M.F.; COWAN, D.D.; LUCENA, C.J.P.; SMITH, D. An
experience using JASMINUM - formalization assisting with the design
of user interfaces. 18 p. Eng. E-mail: lucena@inf.puc-rio.br
Abstract: This paper describes experience in using a visual formalism,
called JASMINUM, in the design of the user interface of a structured
document editor called Waterloo Rita. JASMINUM combines concepts
from Abstrac Data Views, with notations from Objectcharts, Statecharts,
and Petri-nets. JASMINUM was motivated by the need for a formal
notation to express directly some aspects of the design of interactive
systems, especially the design of an interactive system through its
user interface. In particular, we show in this paper how the use of
JASMINUM helped to find some design flaws in the existing Waterloo
Rita system, demonstrating that JASMUNUM might be a useful notation
for re-engineering systems.
[MCC24/94]
NOGUEIRA, J.H.M.; PEREZ ALCAZAR, J.J.; FURTADO, A.L. Análise e implementação da teoria formal de
reconhecimento de planos. 54 p.
Port. E-mail: furtado@inf.puc-rio.br
Abstract: The central part of intelligent reasoning resides in the
agent (human or machine) capacity to realize plans and explain them.
Plan recognition process consists in explain observed actions. Plan
recognition complexity appears when we try to infer reasonable plan
of actions which are not explicitly observed, but actions which are
implicit into agent's knowledge. This process is not purely deductive
because it uses a powerful knowledge representation model, heuristics,
and a typical plans library. The main goal of this work was a
implementation of a Plan Recognition System (PRS), based in Kautz's
formal theory. Furthermore, we include new concepts, rules, and
improvements in this theory, creating a hybrid theory. Our plan
recognition system works with this theory treating complete and
incomplete information.
[MCC25/94]
NOGUEIRA, J.H.M.; FURTADO, A.L. Representação do conhecimento em
banco de dados textuais. 26 p. Port. E-mail: furtado@inf.puc-rio.br
Abstract: Attempts to develop a good semantic network that can support
language, reasoning, and information retrieval upon Textual Databases -
TDB is not easy. This work has got as goal to make an overview of the
main models of knowledge representatation in Artificial Intelligence
and at the same time to make the link between this models and Textual
Databases. In spite of complexity of the models, we find out that some
models had little expression and sometimes they were dificult to handle
with TDB. So, we create a new model, TDM (Textual Database Model),
where it is specifical to treat texts.
[MCC26/94]
VELOSO, P.A.S.; MAIBAUM, T.S.E. Logical specifications: 2.
specifications as presentations. 24 p. Eng. E-mail:
bib-di@inf.puc-rio.br
Abstract: The logical approach to formal specifications regards
specifications as axiomatic presentations of theories in standard
first-order logic. We present this view of specifications as theory
presentations, exploring some of its methodological consequences.
Particular attention is paid to underdetermined specification and the
role of error or exceptions. We start by reviewing some syntactical
and semantical concepts pertaining to languages and specifications.
We then discuss how a specification generates its theory as well as
the roles of equality and induction. Errors and underdetermined
specifications are motivated and discussed in view of their role in
developing programs and reasoning about them. Finally we introduce
liberally constrained specifications as more realistic concept of
"good" specification, motivated by what is specified and available
knowledge about it. A collection of example specifications is also
provided. This report is draft of the second section of a handbook
chapter. Other reports cover the remaining sections.
[MCC27/94]
CERQUEIRA, P.M.; LEITE, J.C.S.P. Recuperação de requisitos a partir
de especificações estruturadas - um estudo de caso. 17 p. Port.
E-mail: julio@inf.puc-rio.br
Abstract: No English abstract provided.
[MCC28/94]
AMARAL, F.C.V.; MILET, J.R.L.; LANZELOTTE, R.S.G. Utilizando a
metodologia OMT para uma aplicação de banco de dados orientado a
objetos. 35 p. Port. E-mail: bib-di@inf.puc-rio.br
Abstract: The Object-Oriented Database Management Systems (OODBMS)
have become established as alternative to applications that must
manipulate non-conventional data. Because of the wealth of concepts,
application designs that use OODBMS are far more complex than
relational systems. The aim of this project is to investigate the
applicatility of the OMT methodology to OODBMS. Therefore, we have
used the OMT to design a multimedia application and herein report
the result of this experiment.
[MCC29/94]
LUCENA, C.J.; CASANOVA, M.A.; VELOSO, P.A.S. Antonio L. Furtado: pioneiro da
pesquisa acadêmcica em bancos de dados. 20 p. Port. E-mail:
lucena@inf.puc-rio.br
Abstract: This work consists of three parts, independently written by
the three authors, all of them long-time colleagues and collaborators
of Prof.Antonio L. Furtado. The first part presents an overview of his
scientific career. The second and third parts address distinct aspects
of his scientific production. Multiple references to a single work were
considered unavoidable, and even desirable. The analysis of the
academic contributions is intertwined with personal views of the author
as colleague and collaborator. This monograph was prepared as part of
the celebrations of the sixtieth anniversary of Prof. Antonio L.
Furtado, and is complemented by appendices, containing a bibliography
with the author's works and a list of his former advisees with
respective dissertation topics.
[MCC30/94]
SCHWABE, D.; ROSSI, G. From domain models to hypermedia applications:
an object oriented approach. 17 p. Eng. E-mail: schwabe@inf.puc-rio.br
Abstract: In this paper we present an object-oriented method for
designing hypermedia applications. The approach divides the development
process in four steps, namely: domain (or content) design, navigational
design, abstract interface design and implementation. We use similar
modeling primitives (object and classes) and abstraction mechanisms
(aggregation, generalization), during the whole process thus improving
traceability; design decisions like the use of complex navigational
structures are made explicit through a uniform notation thus allowing a
coherent document structure that simplifies the construction of a CAHDE.
[MCC31/94]
MARTINS, I.H.; de SOUZA, C.S.; GATTASS, M. Orientação semântica versus
orientação sintática na captura de dados para aplicações
computacionais pelo método dos elementos finitos. 43 p. Port. E-mail:
gattass@inf.puc-rio.br
Abstract: Engineering Systems Based on Planar Subdivision, more
specifically Finite Element Pre-Processors, are powerful tools for
capturing data for analysis and simulation systems. In this class of
software applications direct manipulation interfaces play a very
important role; they allow for visual data entry based on a geometric representation of the artifact. But conceptual models underlying
current interface solutions are not adequate. We have identified some
incongruities between the manipulation process of visual
representations and the data capture process. The former looks for
flexibility in the manipulation of the graphic drawings, whereas the
latter looks for rigidity in the manipulation of semantic objects to
maintain data consistency. Syntactic-driven and semantic-driven
approaches favor one process at the expense of the other. Therefore,
an alternative model is called for. This paper presents a proposal of
one such alternative approach, including a number of contrastive
examples between existing solutions and the proposed ones.
[MCC32/94]
LAUFER, C.; FUKS, H. ACCORD - clichês de conversação para cooperação.
15 p. Port. E-mail: hugo@inf.puc-rio.br
(English
version)
Abstract: Cliches - conversation stereotypes - are state transition
machines that control the sequencing of dialogue events in a
conversation between twoparticipants. Cliches are represented in the
language of ACCORD - a framework for dialogue representation systems
using commitment and legality. The notion of contract - mapped to
Winograd's Conversation for Action diagram - is presented as an example
of the framework's ability for representing conversation cliches for
cooperative work.
[MCC33/94]
VELOSO, P.A.S.; MAIBAUM, T.S.E. Logical specifications: 3. extensions
of specifications. 58 p. Eng. E-mail: bib-di@inf.puc-rio.br
Abstract: We present basic concepts and results concerning extensions
of logical specifications and illustrate their use in constructing
specifications. We start by briefly examining the idea of hidden
symbols in specifications. Then, we introduce some concepts concerning
extensions of languages and of presentations, as well as properties
such as conservativeness and eliminability. We then examine separately
extensions by the introduction of predicates, operations, constants
and sorts, with emphasis on criteria for concervativeness. In
addition to classical definitions, we also consider and compare,
constraints (inner, outer, Skolemisation, and pre and post conditions),
as well as inductive predicates. The methods we consider for
introducing new sorts are product, discriminated union, subsort,
quotient and enumeration, as found in many programming languages.
Finally, we apply these ideas to the treatment of errors and to
construction of specifications. This report is a draft of the third
section of a handbook chapter. Other reports cover the remaining
sections.
[MCC34/94]
LEVY, C.H.; FIGUEIREDO, L.H.; GATTASS, M.; LUCENA, C.J.P.; COWAN, D.D.
IUP/LED: a portable user interface development tool. 29 p. Eng.
E-mail: mgattass@inf.puc-rio.br
Abstract: No English abstract provided.
[MCC35/94]
ALENCAR, P.S.C.; CARNEIRO-COFFIN, L.M.F.; COWAN, D.D.; LUCENA, C.J.P.
Towards a logical theory of ADVs. 18 p. Eng. E-mail:
lucena@inf.puc-rio.br
Abstract: In this paper we motivate and describe a preliminary
logical theory for Abstract Data Views (ADVs) and their associated
Abstact Data Objects (ADOs). Abstract Data Views (ADVs) define
interfaces between application components (ADOs) or between application
components and an "external" environment such as a user or a network.
ADVs are ADOs that have been augmented with event-driven input and
output operations and a mapping that ensures an ADV interface
conforms to the state of its associated ADO. Different ADVs may
view or interact with the same ADO since interfaces can support
alternative "views" of data or modes of interaction, providing the
design satisfies certain consistency obligations. In order to maintain
separation of concerns and promote design reuse, ADOs are specified
to have no knowledge of their associated ADVs. ADVs can be seen as a
way of providing language support for the specification and abstraction
of inter-object behavior. The logical approach identifies the
individual formal units or objects (ADOs and ADVs) that compose the
specification of a system with theories in a temporal logic with a
(global) discrete linear time structure. In this logical formalism,
objects are characterized by their signatures, thus enabling local
reasoning to be performed over components of a system. We also
adopt an open semantics so that objects are not taken in isolation
but can interact with surrounding objects, a pre-requisite for
object composition. Mappings or morphisms are used as a means of
connecting ADOs and ADVs thus formalizing the views relationship
and other ADO and ADV specification constructors. Finally, we present
a proof outline of a modularization theorem of ADOs interpreted
through ADVs in the contex of this logical formalism.
[MCC36/94]
de SOUZA, C.S.; FERREIRA, D.J. Fundamentos de projeto para uma linguagem
visual de programação estruturada. 35 p. Port. E-mail:
clarisse@inf.puc-rio.br
Abstract: This work proposes to create a Visual Programming Language,
where control structures are visually represented by geometric forms
suggestive of the data flow control. Such geometric forms are
formalized according to L-systems rewrintig rules. L-systems support
other kinds of grammars due to generality and simplicity - they allow
for rules to be applied in paralel and for easy mapping from syntax
on to visual representations. By associating L-systems to the so
called "turtle geometry" control structures can be visualized.
Moreover L-systems provide for a syntactic formalization necessary to
every programming language. The proposed Visual Programming
Language is based on Pascal and called Lvpascal.
[MCC37/94]
MERÉ, M.C.; VELOSO, P.A.S. On definition-like extensions by sorts.
19 p. Eng. E-mail: bib-di@inf.puc-rio.br
Abstract: The process of implementing a formal specification on
another one is very important in formal software development
and it can be described in terms of simple basic logical concepts.
Formal specifications are presentations of theories in many-sorted
logic, and an implementation of a formal specification A on another
formal specification C amounts to an interpretation of A into a
conservative extension B of C. An extension consists of the addition
of new symbols and axioms, a simple, but important, special case
being the so-called extensions by definitions. The new symbols
to be introduced correspond to sorts, functions or predicates.
Extensions by the addition of function and predicate symbols are
well studied in the literature. In particular, extensions by
definitions of function and predicate symbols are characterized
by the properties of conservativeness together with eliminability.
Our propose here is to analyse conservative extensions that introduce
new sorts. This is of importance because it occurs often in
implementing formal specifications, when new sorts are "constructed"
from the concrete ones. We specify and analyse some well-known
sort introduction constructs akin to those found in programming
languages, namely cartesian product, discriminated union,
subsorting and quotient. In each case the extension is shown to be conservative and to exhibit a generalised eliminability
property, wich corroborates the intuitive feeling that these
amount to extension by definition of a new sort.
[MCC38/94]
VELOSO, P.A.S.; MERÉ, M.C. Some constructs for sort introduction
in logical specifications. 12 p. Eng. E-mail: bib-di@inf.puc-rio.br
Abstract: The process of implementing a formal specification on
another one is very important in formal software development and
it can be described in terms of simple basic logical concepts
relating the formal specifications involved. Our propose here is to
analyse conservative extensions that introduce new sorts. This is of
importance because it occurs often in implementing formal
specifications, when new sorts are "constructed" from (or
represented in terms of) the concrete ones. We will specify and analyse
some well-known sort introduction constructs akin to those found in
programming languages, namely cartesian product, discriminated union,
subsorting and quotient. This last construct, quotient, even though not
prevalent in programming languages, corresponds to the representation
of the equality on an abstract sort, wich is necessary for a correct
implementation. We will specify each construct by means of a
parameterised formal specification, in that it is a presentation
of a theory in the new, extended language, which is a conservative
extension of its parameter: a presentation of a theory in old language
which describes its applicability condition.
[MCC39/94]
MERÉ, M.C.; VELOSO, P.A.S. The eliminability property in extensions
by sorts. 28 p. Eng. E-mail: bib-di@inf.puc-rio.br
Abstract: The process of implementing a formal specification on
another one is very important in formal software develpoment and can
be described in terms of simple logical concepts as an interpretation
into a conservative extension. An extension consists of the
addition of new symbols and axioms, a simple, but important, special
case being the so-called extensions by definitions. The new symbols
to be introduced correspond to sorts, functions and predicates.
Extensions by the addition of function and predicate symbols are well
studied in the literature. Our purpose here is to analyse the
eliminability property in conservative extensions that introduce
new sorts. This is of importance because it occurs often in
implementing formal specifications, when new sorts are "constructed"
from the concrete ones. We view some known sort introduction constructs, akin those found in programming languages
(namely
cartesian product, discriminated union, subsort and quotient), like
extensions of a base language with the given sorts and study some
common properties to these extensions.
[MCC40/94]
VELOSO, P.A.S.; MERÉ, M.C. On definability properties for sort
introduction constructs. 42 p. Eng. E-mail: bib-di@inf.puc-rio.br
Abstract: The process of implementing a formal specification on
another one is very important in formal software development and can
be described in terms of simple logical concepts as an interpretation
into a conservative extension. An extension consists of the addition
of new symbols and axioms, a simple, but important, special case being
the so-called extensions by definitions. The new symbols to be
introduced correspond to sorts, functions and predicates. Extensions
by the addition of function and predicate symbols are well studied
in the literature. Our purpose here is to analyse definability
properties in conservative extensions that introduce new sorts. We
regard some usual sort introduction constructs, akin those found
in programming languages (namely cartesian product, discriminated
union, subsort and quotient), as extensions of a parameter
specification with the given sorts and study some important
properties to these extensions.
[MCC41/94]
SCHWABE, D; ROSSI, G. Building hypermedia applications as
navigational views of information models. 10 p. Eng. E-mail: dschwabe@inf.puc-rio.br
Abstract: In this paper we present a novel approach for defining
hypermedia applications as navigational views of an object-oriented
hypermedia schwma. We briefly describe OOHDM (Object-Oriented
Hypermedia Design Model) using an academic information system as
a concrete example to illustrate each modeling construct. We further
analyze the whole process of hypermedia applications building focusing
mainly on navigational design. The approach we propose allows clean
separation of content design, navigational design and abstract
interface design. Such separation of concerns allows seamless evolution
from abstract domain models to concrete implementation of hypermedia
applications, especially those in which there is a wide range of
information to be handled.
[MCC42/94]
BARBOSA, S.; SCHWABE, D. Navigation modelling in hypermedia
applications. 21 p. Eng. E-mail: dschwabe@inf.puc-rio.br
Abstract: A distinguishing feature of hypermedia applications is the
possibility of navigational access by the user. Although this type of
access can be an advantage, there many problems associated with it,
for example user disorientation ("lost in hyperspace"). This paper
presents the concept of navigational context, which is used to design
the navigation structure of a hypermedia application. Navigational
contexts are defined in the framework of the Object Oriented
Hypermedia Design Methodology, which strives to systematize the
process of hypermedia application design, from the conceptual
modeling phase all the way to implementation. Throughout the paper,
examples of the use of navigational contexts are shown using
Microsoft's Art Gallery CDROM application.