Monografias em Ciência da Computação
1997
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,
Pontífícia 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
[MCC01/97]
ZUKIN, M.; FUKS,H.; DALCOL, R.R.T. Digital communication technology:
connecting design, engineering and manufacturing. 33 p. Eng. E-mail:
hugo@inf.puc-rio.br
Abstract: Companies increasingly need to reduce lead times in product
development as a way to get products onto the market faster and more
efficiently. Digital communication integrating design, engineering and
manufacturing can greatly improve the product development process through
concurrent engineering and overlapping activities. This paper
presents a case study on how digital communication can overcome
temporal and geographical barriers in the exchange of information,
enhancing a collaborative and cooperative environment. The project
studied was a vacuum cleaner developed in Electrolux-Italy, in which
the first author of the paper participated as Senior Product Designer.
In this paper, the authors describe and analyze the process, and
then elaborate a scenario that contemplates networks for digital
communication, and a technology infra-structure for the process
highlighted.
[MCC02/97]
VELOSO, P.A.S. On algorithmic fork relations and programs. 29 p. Eng.
E-mail: bib-di@inf.puc-rio.br
Abstract: We continue examining the adequacy of an extended relational
framework for program development. We argue that a set of "algorithmic"
symbols, selected on the basis of effectiveness considerations,
provides an adequate programming language. This is established by
extending a natural programming language correspondence to show that
these algorithmic symbols can express only programs and all programs
(including nondeterministic ones). In two previous reports, we
introduced the question of adequacy of an extended relational framework
for program development. We argued that the familiar apparatus
of binary relations must be extended to be appropriate for programming
and we also examined the nature of such an extension obtained by
considering relations on structured universes with new structural
operations. In another report we selected, by effectiveness
considerations, a set of symbols deserving the name "algorithmic"
and we also outlined a programming language correspondence indicating
that these algorithmic symbols are adequate for expressing programs.
In this report we examine more closely the algorithmic part of this
fork relational framework and its ability to express programming
behaviours. We argue that the set of algorithmic symbols, selected on
the basis of effectiveness considerations, provide an adequate programming language. This envolves the establishment of two
inclusions. On the one hand, our algorithmic part expresses only
computing-like behaviours. On the other hand, every program, even a
nondeterministic one, can be expressed in this algorithmic part.
These inclusions are established by extending the natural programming
language correspondence.
[MCC03/97]
CAFEZEIRO, I.; HAEUSLER, E.H.; HAEBERER, A.M. From diagram to code
via attribute grammar. 38 p. Eng. E-mail: hermann@inf.puc-rio.br
Abstract: This report describes within a formal approach how to
generate code from a graphical description based on diagrams. The
method is general enough not to consider specific methodology nor
a specific target programming language. The essence of the method
consists of combining Object Oriented ideas to capture the generality
of diagrams and Attributed Grammars to solve the context-sensitive
feature. A case study is presented.
[MCC04/97]
PRATES, R.O.; de SOUZA, C.S.; GARCIA, A.C.B. Semiotic framework for
multi-user interfaces. 24 p. Eng. E-mail: clarisse@inf.puc-rio.br
Abstract: Semiotic approaches to user interface designs have shown that
system interfaces are messages sent from the designers to the users.
It is through the system's interface that the designers tell the
users the problems the system is able to solve and how the users
should interact with it to solve these problems. In a multi-users environment this message is more complex, since the designers must also
tell the users how to interact in the group. To create such message
is not an easy task and designers should be provided with a good
designing tool. In this article we present a semiotic framework that
is the first step in the direction of the construction of a multi-users
interface design environment. The framework has three dimensions:
action, communication and observation and provides support
for the analysis of multi-users system's interface and undestanding
of interactions in the group. It can also be a helpful guide
to designers of multi-users interfaces.
[MCC05/97]
CUNHA, C.K.V.; de SOUZA, C.S. The role of explanation systems in
multiagent applications. 7 p. Eng. E-mail: clarisse@inf.puc-rio.br
Abstract: This paper discusses the role of Explanation Systems in
multiagent applications. Our starting point is an Active Design
Documentation (ADD) tool. Its typical explanation facility is
adapted in order to explore the resources available in multiagent
environments. Following a Semiotic Engineering approach, explanations
in MultiADD (Multiagent ADD) are used as a means of communication
between system designer and system user, and provide a common
linguistic embedding for end-user communication during negotiation
and conflict mitigation.
[MCC06/97]
FURTADO, A.L. Plots of narratives over temporal databases. 12 p. Eng.
E-mail: furtado@inf.puc-rio.br
Abstract: An operation-based notion of plots of narratives is
introduced, to summarize events happening to objects in the temporal
database of an information system. The method proposed for modelling
and handling plots, invloving the application of a Plan-recognition
facility, is shown to be useful for various purposes, including
problem-detection and decision support. An interdisciplinary approach
is adopted, utilizing results from studies on literary theories.
[MCC07/97]
CIARLINI, A.E.M.; FURTADO, A.L.; LIFSCHITZ, S. Modelando enredos de
narrativas como planos. 22 p. Port. E-mail: furtado@inf.puc-rio.br
Abstract: The present work describes a method for modelling plots
of narratives as plans, which permits to handle automatically the
classification, complementation, adaptation and generation of plots.
In particular, are presented the results of applying these ideas to
modelling plots belonging to the literary gender of fairy tales,
through a prototype system integrating plan recognition and
generation. The method reflects the influence of literary theories,
mainly from the Structuralist school.
[MCC08/97]
MILIDIU, R.L.; LABER, E.S. Some bounds on the redundancy of
length-restricted prefix. 12 p. Eng. E-mail: milidiu@inf.puc-rio.br
Abstract: No English abstract provided.
[MCC09/97]
FURTADO, A.L., Combinando programação funcional com programação em lógica. 21 p. Port. E-mail: furtado@inf.puc-rio.br
Abstract: A simple strategy for combining the functional and the
logical programming paradigms is proposed , through the addition
of a functional component to the Prolog language. The component
allows user-defined functions and functional operators, as well
as the application of a number of predefined functional forms.
Several examples are presented illustrating, among other features,
the integrated use of functions and predicates in the same
expression.
[MCC10/97]
de SOUZA, C.S.; LEITE, J.C. A framework for the semiotic engineering of
user interface languages. 12 p. Eng. E-mail: clarisse@inf.puc-rio.br
Abstract: Semiotic Engineering is a theoretically based approach to
user interface design in which the interface is seen as a message sent
from designers to users carried by the computer medium and whose content
is the software functionality and the interaction model. In this paper,
we describe a framework founded in semiotic theory to this design
process. It provides a Model of User Interface Design Language
which is a meta-language for the designer to express User Interface
Messages and the Interaction Language. Our emphasis here is not in
aesthetic aspects of user interfaces, but in the interactive and
performing nature of the interface message as it is carried
throughout the computational medium.
[MCC11/97]
de SOUZA, C.S.; LEITE, J.C. Projeto de interfaces de usuário. 62 p.
Port. E-mail: clarisse@inf.puc-rio.br
Abstract: No English abstract provided.
[MCC12/97]
de SOUZA, C.S. Supporting end-user programming with explanatory
discourse. 6 p. Eng. E-mail: clarisse@inf.puc-rio.br
Abstract: The need to empower end users with programming capacities
in order to adapt and extend software applications brings forth the
opportunity to examine and explore semiotic aspects in computing.
This paper discusses some of these aspects within a knowledge-based
extensible environment where (a) software designer can explain their
rationale to users and (b) differential discourse for user-system
interaction and designer-user communication fosters a better
understanding of the application's model and features.
[MCC13/97]
FRIAS, M.F.; HAEBERER, A.M.; VELOSO, P.A.S. A finite axiomatization
for fork algebras. 11 p. Eng. E-mail: bib-di@inf.puc-rio.br
Abstract: Proper fork algebras are algebras of binary relations over
structured set. The underlying set has changed from a set of pairs to
a set closed under an injective function. In this paper we present
a representation theorem for their abstract counterpart, that
entails that proper fork algebras whose underlying set is closed under
an injective function constitute a finitely based variety.
[MCC14/97]
FONTOURA, M.F.; LUCENA, C.J.P. Um ambiente para modelagem e execução de
processos. 16 p. Port. E-mail: lucena@inf.puc-rio.br
Abstract: This work presents the architecture and main features of an
environment for process modeling and analysis. The software and business
processes are modeled through a process language based on
Petri Nets which handles all important objects for process definition
such as artifacts, roles, and tools.
[MCC15/97]
BRAGA, C.O.; STAA, A.v.; LEITE, J.C.S.P. A hybrid architecture for
documentation production. 17 p. Eng. E-mail: arndt@inf.puc-rio.br
Abstract: Good documentation is essential for the production and
evolution of quality software. Based on a survey on program
documentation, we propose a documentation architecture that aims
to fulfill several requirements of an ideal solution. The
architecture integrates a powerful transformation system (Draco-PUC)
and a versatile CASE tool (Talisman) in order to produce documents
using reverse engineering strategies. We have implemented such
approach in a prototype tool called Documentu, which uses a database
to store system wide information and uses a standard hypertext browser
to help the access and navigation of the system documentation. The
prototype was used in a large scientific system in an oil company,
with very positive results.
[MCC16/97]
FIORINI, S.T.; LEITE, J.C.P.; LUCENA, C.J.P. Descrição de padrões de
processo em um ambiente automatizado para modelagem de processos.
18 p. Port. E-mail: julio@inf.puc-rio.br
Abstract: This article investigates problems related to process
patterns. Most of the proposed patterns' descriptions heavily rely
on natural language. We have analysed some of these proposals and
presented an alternative based on structured natural language
descriptions. Our strategy leads to a better presentation of the
patterns as well as reduces the problem of ambiguity. Our proposal
is integrated with an existing process environment.
[MCC17/97]
LIFSCHITZ, S.; LIMA, I.N. O ambiente de integração SGBD e Web. E-mail: sergio@inf.puc-rio.br
Abstract: [The document has not been published]
[MCC18/97]
LIFSCHITZ, S.; LIMA, I.N. Modelos de conectividade SGBD e Web. E-mail: sergio@inf.puc-rio.br
Abstract: [The document has not been published]
[MCC19/97]
FUKS, H.; TAROUCO, L. Chaining CU-SeeMe reflectors: the SBRC' 96
experiment. 10 p. Eng. E-mail: hugo@inf.puc-rio.br
Abstract: This paper reports the experiment involving a live transmission-video and audio of some events of the XIV Brazilian
Symposium of Computer Networks. This was the first live transmission
of this kind using the Brazilian Internet backbone. We chose to use
CU-SeeMe softwareclient and reflectorwhich made it possible to build
a reflector chain, especially designed to broadcast the transmission
throughout Brazil.
[MCC20/97]
FUKS, H.; LAUFER, C. Cooperative administration of a public CU-SeeMe
reflector. 7 p. Eng. E-mail: hugo@inf.puc-rio.br
Abstract: This article proposes a groupware architecture for WWW
applications, independent of environment or platform, that can
integrate diverse services. We present a WWW site prototype for
cooperative administration of a public CU-SeeMe reflector. Internet
software components are put together to offer a set of services.
[MCC21/97]
GARCIA, A.V.; HAEUSLER, E.H.; HAEBERER, A.M. A semantic approach
to the solution of the legacy code. 19 p. Eng. E-mail:
hermann@inf.puc-rio.br
Abstract: This work proposes a semantic approach to the legacy code problem and presents preliminary
results based on a working prototype.
A functional specification of the source code is obtained by means of
the semantic specification of the language in which it is written. The
specification is then translated into an object oriented language.
Both tasks are achieved by means of transformation tools.
[MCC22/97]
VELOSO, P.A.S. On simpler (equational) presentations for fork
algebras and their relational reducts. 22 p. Eng. E-mail:
bib-di@inf.puc-rio.br
Abstract: A fork algebra is a relational algebra enriched with a new
binary operation. This class of algebra was introduced because its
equationalcalculus has applications in program construction. It also
has some interesting connections with algebraic logic. In this report
we examine some simpler presentation for fork algebras and their
relational reducts. These alternative characterisations comes from
the consideration of special (pairs of) elements in relational
algebras. Their adequacy comes from an analysis of the proof of
representability where it was implicit, as well as from properties
of these special pairs of elements. This approach provides interesting
insights and leads to (equational) presentations with convenient
structures.
[MCC23/97]
SILVA, S.R.P.; BARBOSA, S.D.J.; de SOUZA, C.S. Communicating different
perspectives on extensible software. 17 p. Eng. E-mail:
clarisse@inf.puc-rio.br
Abstract: Actual End-User Programming is as far away from us as is in
an actual End-User Perception of the rationale beneath software design.
One of the major obstacles to achieving this goal is the discontinuity
among user interface language, end-user programming language, and
documentation language. Objects referred in one of them are not easily
identifiable as the same referred to by the others. In this paper,
we analyze this situation from a semiotic perspective and propose
interconnected environment architecture and language design guidelines
that we beleieve can narrow the gap there is to bridge.
[MCC24/97]
CARVALHO, S.E.R.; CRUZ, S.O.; OLIVEIRA, T.C. State depedent behavior
in the ARTS project. 12 p. Eng. E-mail: bib-di@inf.puc-rio.br
Abstract: In object systems, the behavior of an object, when
responding to a stimulus, may depend on the values of its components
at the time, or on its state. Several development methods recommend
the handling of state dependent behavior, at different stages during
system construction. In this paper we describe the solution adopted in
ARTS, a second generation development system for real-time OO
applications. We use a variation of the State design pattern, in the
context of 2GOOD, a CASE tool providing graphical user interfaces, and
DDL, a design description language for the textual representation of
interface diagrams.
[MCC25/97]
FEIJÓ, B. Virtual environments for CAD systems. 18 p. Eng. E-mail:
bruno@inf.puc-rio.br
Abstract: Irrespective to the built-in degree of Artificial
Intelligence, any tool for assisting structural and mechanics
engineering design is deeply rooted into 3D environments. However, the
question of 3D virtual worlds is not clearly presented in the AI-based
CAD literature. This paper contributes to the understanding of Virtual
Environments in CAD systems, in a way more closely aligned with the
design task environment and the perspective needs of CAD users. This
paper is also a pratical guide for CAD researchers and engineers who
want to explore the possilities of VE technology.
[MCC26/97]
ALMEIDA, E.S.; MAFFEO, B. Especificação de estruturas conceituais básicas
através de redes de Petri compactas. 45 p. Port. E-mail:
maffeo@inf.puc-rio.br
Abstract: This work presents procedures to formally specify each
primitive operational activity contained in activity schemes, that
model systems behavior when the Essential Model is used as
conceptual framework. This formal specification employs Compact
Petri Nets as representation language and, for each procedure
presented, the primitive operational activity to be specified
belongs to a conceptual pattern typically found in essence modelling.
It is suggested that these procedures should be employed in formal
specifications of large systems based Compact Petri Nets, since its
use in connection with the structures commonly found in the Essential
Model allows a gradual control of representational complexity,
otherwise excessive. It is also believed that significant gains of
quality and productivity in the systems development process should be
achieved through reuse of these conceptual pattern specifications.
[MCC27/97]
ROSSETI, I.C.M. Balanceamento de carga em ambientes distribuídos.
11 p. Port. E-mail: bib-di@inf.puc-rio.br
Abstract: Many load balancing techniques have been proposed, in
order to obtain improvement in the performance of parallel
applications. This paper presents some existing load balancing
algorithms. These algorithms are presented according to an analytical
model called matrix iterative model, that was chosen for the variety
of load balancing algorithms which it may represent.
[MCC28/97]
FERREIRA, S.B.L.; LEITE. J.C.S.; CARVALHO, S.E.R.; MELO, R.N.
Requisitos não funcionais para interfaces com o usuário - um estudo do
aspecto cor. 15 p. Port. E-mail: julio@inf.puc-rio.br
Abstract: The present paper presents an contribution to the
requirements engineering by researching the non functional
requirements, concerned to the design of user interface. The goal of
these research is to obtain a friendly interaction so that the user
feels comfortable in using an interface. The requirements of any
system are closely related to the system objectives and they must be
very well defined. The non functional requirements are briefly
presented and an especial attention is given to those related to the
user interface. To finish, is presented a complete study of several
features involved in the use of color and its effects on the project
of an interface.
[MCC29/97]
CARVALHO, S.E.R. DDL: an object oriented Design Description Language.
21 p. Eng. E-mail: bib-di@inf.puc-rio.br
Abstract: Object-oriented designs are usually expressed graphically,
via static and dynamic diagrams. When translated into executable
code, diagram characteristics are lost in low-level programming
language details. To prevent discontinuities, designs should be
expressed in languages textually describing the same discourse.
This report presents one such language, DDL, being used intermedially
in a CASE tool allowing the automatic generation of C++ code. This
graphical-textual match furthers project documentation, correctness
verification, and traceability, for example.
[MCC30/97]
BARBOSA, S.D.J.; de SOUZA, C.S.; LUCENA, C.J.P. Supporting
metaphorical mappings to facilitate end-user programming. 9 p. Eng.
E-mail: clarisse@inf.puc-rio.br
Abstract: End-user programming still lacks easy-to-use mechanisms
that support programming from end-users' point-of-view. We follow
the premise that metaphors are in the grounding of our conceptual
system, and recognize that the extensions end-users want to make
are usually modifications upon an application's existing functionality.
We propose an environment that makes use of an application's ontology
to recognize and present possible ways to generate new code. We
describe mechanisms that suggest modifications upon existing code
based on metaphorical mappings between the ontology elements. We
believe our approach helps end-users learn how the application
actually works and encourages them to make software extensions and
therefore get their tasks done more efficiently.
[MCC31/97]
LEITE, J.C.S.P. Workshop de pesquisas do Departamento de Informática
- 1996. 52 p. Port. E-mail:julio@inf.puc-rio.br
Abstract: The report presents the Workshop abstracts of ongoing researches
at Departamento de Informática - PUC-Rio.
[MCC32/97]
ANDRADE, A.M.S., VELOSO, P.A.S. Uma abordagem lógica do PDS. 24 p.
Port. E-mail: bib-di@inf.puc-rio.br
Abstract: We present a logical approach to the software development
process, based on the objects that make up this process: application,
specifications, program and virtual machine. We propose a diagram for
the correctness of the process by taking into account its synthetic
aspect and the observable-theoretical dichotomy coming from the
distinct nature its objects. We compare this approach to a presentation
in the formalism of problems and show that the correctness relationship
between the objects of the software development process amount to
relaxation relationship between the corresponding problems.
[MCC33/97]
MILIDIÚ, R.L.; LABER, E.S. Improved bounds on the inefficiency
of length-restricted prefix codes. 22 p. Eng. E-mail:
milidiu@inf.puc-rio.br
Abstract: (abstract provided includes many formulas, thus not possible to reproduce
here in).
[MCC34/97]
ARAGÃO, M.V.S.; UCHOA, E. The gamma-connected assignment problem.
17 p. Eng. E-mail: poggi@inf.puc-rio.br
Abstract: Given a graph and costs of assigning to each vertex one
of K different colors, we want to find a minimum cost assignment
such that no color induces a subgraph with more than a given number
gamma_k of connected components. This problem arises in the context
of contiguity-constrained clustering, but also has a number of other
possible applications. We show the problem to be NP-hard. Nevertheless,
we derive a dynamic programming algorithm that proves the case where
the underlying graph is a tree to be solvable in polynomial time.
Next, we propose mixed-integer programming formulations for this
problem that lead to branch-and-cut and branch-and-price algorithms.
Finally, we introduce a new class of valid inequalities to obtain an
enhanced branch-and-cut. Extensive computational experiments are
reported.
[MCC35/97]
GOMES, P.C.R.; FEIJÓ, B.; CERQUEIRA, R.F.G.; IERUSALIMSCHY, R.
Reactivity and pro-activeness in virtual prototyping. 11 p. Eng.
E-mail: bruno@inf.puc-rio.br
Abstract: Virtual prototyping becomes much more interesting when 3D
solids are dynamic distributed objects on heterogeneous platforms.
However, the dynamic nature of the design process requires a deeper
investigation on reactive and pro-active 3D objects. This paper
proposes the concept of Extended Constraint Graphs with bidirectional
reactivity and one-way actions to represent reactivity and pro-activeness in digital mock-ups. Also, this paper presents an
original approach to deal with the dynamic nature of virtual mock-ups
through the use of an interpreted language Lua and a CORBA binding
called LuaOrb. Moreover, this work presents a CORBA model for virtual
prototyping based on the geometry bus ACIS in which objects and
attributes are created and modified at run time.
[MCC36/97]
MOURA, L.M.; LUCENA, C.J.P. O ambiente visual spider para o
desenvolvimento de aplicações na Internet. 16 p. E-mail:
lucena@inf.puc-rio.br
Abstract: Visual composition is the interative development of
applications by the direct manipulation of reusable components.
We believe that the visual composition approach directly deals with
the complexity of large software systems making the development
easier, more flexible, and more understendable. This is accomplished
by implementing abstraction, reuse, and visualization concepts. The
developer becomes a component builder and no longer creates large
applications that are hard to maintain and enhance. The user has the
freedom to choose the components from different developers until the
desired functionality is achieved. The visual environment Spider
allows the creation of different kinds of applications. In this
article we give special attention to the creation of Internet
applications.
[MCC37/97]
MEDIANO, M.R. OPS: um subsistema extensível e configurável de
armazenamento de objetos persistentes para bancos de dados geográficos. 16 p. Port. E-mail: bib-di@inf.puc-rio.br
Abstract: The persistent object storage subsystem OPS proposes an
extensible and configurable model through which it is possible to
model, implement and combine different database technologies to
provide new capabilities or to obtain performance improvements.
OPS is based on four abstractions: persistent object, object data
area, object manager and media.
[MCC38/97]
VELOSO, P.A.S. On some connections between Logic and Computer
science. 25 p. Eng. E-mail: bib-di@inf.puc-rio.br
Abstract: This report examines some important connections between
Logic and Computer Science. A brief historical overview highlights
some contributions of Logic and logicians to the development of the
Science of Computing. Then, two more recent connections motivated
by stepwise development of reliable programs from specifications,
namely Logical Specifications and Fork Algebras, are summarised.
Such connections illustrate important bridges between Logic and
Computer Science. They also indicate one may expect the emergence
of more and stronger links, contributing to the development of
both sciences.
[MCC39/97]
MILIDIÚ, R.L.; LABER, E.S.; PESSOA, A.A. Improved analysis of FGK
algorithm. 13 p. Eng. E-mail: milidiu@inf.puc-rio.br
Abstract: (abstract provided includes many formulas, thus not possible to reproduce
here in).
[MCC40/97]
VELOSO, P.A.S. Logic and Computer Science: logical specifications.
37 p. Eng. E-mail: bib-di@inf.puc-rio.br
Abstract: This report examines in some detail Logical Specifications
as a connection between Logic and Computer Science motivated by
stepwise development of reliable programs from specifications. We
emphasise the so-called 'liberal' specifications, which appeared
with the aim of providing a framework with solid foundations that is
close to programming practice. A logical specification is an axiomatic
theory, which is regarded as presenting properties of the available
resources. We first introduce the basic ideas by examining the role
of logical specifications in the programming process and the refinement
steps involved. Then we examine some modularity properties and their
connection with interpolation and finally some constructs for the
introduction of new sorts. Such connections illustrate important
bridges between Logic and Computer Science. They also indicate that
one may expect the emergnce of more and stronger links, contributing
to the development of both sciences.
[MCC41/97]
VELOSO, P.A.S. Computer Science and Logic: fork algebras. 41 p.
Eng. E-mail: bib-di@inf.puc-rio.br
Abstract: This report examines in some detail Fork Algebras as a
connection between Computer Science and Logic motivated by the
methodical construction of reliable programs from specifications.
A fork algebra is a relational algebra enriched with a new binary
operation, called fork. Such algebras arose from programming
motivations, with the aim of providing a wide-spectrum formalism
for program construction and derivation. They also have some interesting connections with algebraic logic. We first review the idea of using relations for programming, which
motivates an
extension of the relational apparatus in order to provide an
adequate framework for program construction. We then examine the
abstract and set-based versions of fork algebras, showing that the
former can represented by the latter. Next, we consider the algebraic
fork calculus and argue that it provides an equational counterpart
for first-order logic. Finally, we examine some other properties of
these algebras, namely a category isomorphic to that of fork algebras,
suggesting a simpler equational axiomatisation for them, how much a
finite or infinite relational algebra constrains it possible fork
expansion, and what extent fork algebras of relations can be endowed
with a cartesian fork operation, induced by real pair formation. Such
connections illustrate important bridges between Computer Science and
Logic. They also indicate that one may expect the emergence of more
and stronger links, contributing to the development of both sciences.
[MCC42/97]
UCHOA, E.M.A.; LIFSCHITZ, S.; MELO, R.N. HEROS: um sistema de
bancos de dados heterogêneos usando CORBA. 42 p. Port. E-mail:
rubens@inf.puc-rio.br
Abstract: Object oriented software standards have been considered
to coordinate, with the desired flexibility, and integrate, the
information processing resources within a given network. With
respect to heterogeneous database systems architectures, these
standards can be used for the integration and interaction among
the heterogeneous components, which may increase the federation
adaptability and scalability to new environments. This work gives
a complete presentation of HEROS, a heterogeneous object oriented
database system, and discusses its implementation using CORBA for
components interoperability.
[MCC43/97]
CERQUEIRA, R.; IERUSALIMSCHY, R.; RODRIGUEZ, N.L.R. A Dynamic approach
for composing CORBA objects. 13 p. Eng. E-mail: noemi@inf.puc-rio.br
Abstract: This paper describes LuaOrb, a binding between the
extension language Lua and CORBA. Like other CORBA bindings,
this binding allows a program to manipulate CORBA objects in the
same way it manipulates local objects. Unlike conventional
bindings, however, LuaOrb is based on a dynamic approach, mapping
the dynamic character of CORBA to the dynamic type system of Lua.
This binding brings together CORBA reuse facilities with the
flexibility provided by an interpreted language, fulfilling the "command
center'' concept proposed by Siegel.
[MCC44/97]
ALMEIDA,E.S.; MAFFEO, B. Especificação de estruturas conceituais básicas
através da lógica de predicados. 19 p. Port. E-mail:
maffeo@inf.puc-rio.br
Abstract: This work defines a representation language and
illustrates procedures to formally specify each primitive
operational activity contained in activity schemes that model
systems behavior when the Essential Model is used as conceptual
framework. The representation language is based on predicate
logic and, for each procedure illustrated, the primitive
operational activity to be specified belongs to a conceptual
pattern typically found in essence modeling. It is suggested that these procedures should be employed in formal specifications
of large systems based on logic languages, since its use in
connection with the structures commonly found in the Essential
Model allows a gradual control of representational complexity,
otherwise excessive. It is also believed that significant gains
of quality and productivity in the systems development process
should be achieved through reuse of these conceptual pattern
specifications.
[MCC45/97]
LUCENA, C.J.P.; FUKS, H.; MILIDIÚ, R.; MACEDO, L.T.; SANTOS, N.;
LAUFER, C.; FONTOURA, M.F.; NEVES, P.; CRESPO, S.; CARDIA, E. E.;
TORRES, V. AulaNet TM - um ambiente para desenvolvimento e manutenção
de cursos na WWW. 16 p. Port. E-mail: lucena@inf.puc-rio.br
Abstract: As yet there are no experts in the application of information
technology to learning and training. However this area
is becoming a major one in the Internet. Researchers in industry
and in the academic world are developing models and products for
training and education based on the Web. In this work we present
AulaNet, an environment for the creation and maintenance of
Web-based courses designed for the layman. We also compare
AulaNet to other similar Web-based environments.
[MCC46/97]
MOURA, L.M.; LUCENA, C.J.P.; STAA, A.v. A spider environment. 25 p.
Eng. E-mail: arndt@inf.puc-rio.br
Abstract: Visual composition is an interactive development of
different applications by the direct manipulation of reusable
components. We believe that the visual composition approach deals
directly with the complexity of large software systems making their
development easier, more flexible, and easier to be understood.
This is accomplished by implementing abstraction, reuse, and
visualization concepts. The developer becomes a component builder
and no longer creates large applications that are hard to maintain
and enhance. The user will have the freedom to choose the
components he needs to build an application, and to mix and match
components from different developers until the desired functionality
is achieved. The visual Spider environment allows the creation of
different kinds of applications.
[MCC47/97]
SILVA, S.R.P.; de SOUZA, C.S.; IERUSALIMSCHY, R. A communicative
approach to end-user programming languages. 25 p. Eng. E-mail:
clarisse@inf.puc-rio.br
Abstract: Motivated by the goal of empowering people with programming
capabiliteis, we propose a framework for the design of applications
that more adequately support end-user extension programming. This
framework is grounded on a communication architecture that draws on
the availability of the aplication's design knowledge base. We
propose that together with any modality of end-user programming
there must be a corresponding modality of explanation for end users.
Whereas the former allows end users to extend the application's
functionality, the latter is essencial to help end users elaborate
on their understanding of the application's rationale. In this paper,
we focus on design choices, an end-user programming language for our
framework. We are looking for design guidelines for a language with
good communication resources, in which end users can take advantage
of their common sense knowledge to program and update the application's
design knowledge base. We propose a plan-based programming language, guided by the fact that end users are familiar with plan-based
procedural descriptions. We analyze end-users' daily plan expressions,
like "recipes" and "do-it-yourself books", matching their
communication resources against current programming languages and
identifying the main issues that should be addressed to create a better
semiotic continuum between user-interface languages and end-user
programming languages.