38243163
Querying Hypermedia Applications in an Object-Oriented Framework
47231847
Enhancing a requirements baseline with scenarios
Scenarios are well recognized as an important strategy towards understanding the interface between the environment and the system, as well as a means to elicit and specify software behavior. We have a broader understanding of scenarios: for us, a scenario is an evolving description of situations in the environment. Our proposal is framed by Leite's (1995) work on a client-oriented requirements baseline, which aims at modeling the external requirements of a software system and its evolution. Scenarios start by describing the environmental situation, according to the main actions performed outside the software system. Scenarios also help the clarification of the interrelation between functional and non-functional requirements. We have validated our strategy and related representations based on case studies of a real situation.
7589770
Specifying Quality Characteristics and Attributes for Websites
In this work, we outline more than a hundred characteristics and attributes for the domain of academic sites in order to analyze the quality requirement tree and a way to specify them. These elements are used in a quantitative methodology for assessment, comparison, and ranking processes. The proposed Web-site Quality Evaluation Methodology (QEM) can be a useful approach to assess the quality in different phases of a Web product life cycle. In the academic study, we have observed three different evaluation audiences regarding visitor users: current and prospective students, academic personnel, and research sponsors. Besides, the aim of this work is to show a hierarchical and descriptive specification framework for characteristics, subcharacteristics and attributes. This framework is a key underlying piece in the construction of a hyperdocumented evaluation tool. Finally, some results are presented and concluding remarks are discussed.
11116452
The object-oriented hypermedia design model
H ypermedia applications typically include complex information , and may allow sophisticated navigation behavior. The Object-Oriented Hypermedia Design Method (OOHDM) [4] uses abstraction and composition mechanisms in an object-oriented framework to, on one hand, allow a concise description of complex information items, and on the other hand, allow the specification of complex navigation patterns and interface transformations. In OOHDM, a hypermedia application is built in a four-step process supporting an incremental or prototype process model. Each step focuses on a particular design concern, and an object-oriented model is built. Classification, aggregation and generalization/specialization are used throughout the process to enhance abstraction power and reuse opportunities. Figure 1 summarizes the steps, products , mechanisms and design concerns in OOHDM. Domain Analysis In this step a conceptual model of the application domain is built using well-known object-oriented modeling principles [3], augmented with some primitives such as attribute perspectives (multiple-valued attributes, similar to HDM perspectives [1]). Conceptual classes may be built using aggregation and generalization/special-ization hierarchies. There is no concern for the types Abstract interface objects, responses to external events, interface transformations Running application
1003988
Solving Systems of Equations over Hypersets
A universe composed by rational ground terms ia characterized (both constructively and axiomatically), where the interpreted set constructs land •ith (the latter designating the element insertion operation) coexist with free Herbrand functors. Ordinary syntactic equivalence must be superseded by an equivalence relation ~. between trees labelled over a signature, that suitably reflects the semantics of vith. Membership (definable as "d E t =oo~ ( t vith d) ~ t") meets the non-well-foundedn,ess property characteristic of hyperset theory. An algorithm for solving the NP-eomplete unification problem pertaining to hollow hyperset terms is provided, and shown to be totally correct. An application to the matching of finite state automata is hinted at. Introduction With this paper we wish to contribute to the field of constraint logic programming mainly in two ways. First, by characterizing hyperseb both constructively and axiomatically ( cf. See. 2, 3); then, by specifying a procedure for normalizing constraints of the most basic kind over hypersets. Our procedure will be shown to always terminate and to give the proper results (cf. Sec. 4). A by-product of our constraint normalization procedure is an algorithm for solving a novel NP-complete unifictJtion problem pertaining to hypersets, which has direct applications on its own: it can be used, for instance, to determine whether two finite state automata characterize the same language (cf. See. 5). Hypersets of the kind we will propose are very intimately related to Aczel's nonwell-founded sets (ef. [1]), but they all have finite cardinality and height; moreover they are hybrid, in that their construction involves free Herbrand fun.etors. The finiteness restriction comes from our willingness to regard hypersets as tnstanees of an algorithmic data structure; the proposed hybridization comes from our goal to Q Until. tli Pi .. , Dip. di Inlonn.atica. Cono ltalia -40, 561~Piaa (1). do'fiertdi .uaipi.il ¢ U~ti•. tli Roma "L. Sa,ienza", Dip. di Inl. e Siat. Via Salaria, 113. 00198-Rom&. o.odeoe .. si.dis.uairo .. l.il 6 Uniw. tli Utli"e, Dip. di Matematica e Inlormatica. Via Zanon, 6. 33l~Udine (1). policrited!.i.1111iad.il • Uftiw. tli Parma, Dip. di Matematica. Via M. D'Azepo, 85/ A. -43l~P.vma (1). 1ro••iep~t.aat~ . 1111ipr . il
15161679
On the Representation and Management of Finite Sets in CLP Languages
We review and compare the main techniques considered to represent finite sets in logic languages. We present a technique that combines the benefits of the previous techniques, avoiding their drawbacks. We show how to verify satisfiability of any conjunction of (positive and negative) literals based on =,⊆,∈, and ∪,∩, \, and ||, viewed as predicate symbols, in a (hybrid) universe of finite sets. We also show that ∪ and || (i.e., disjointness of two sets) are sufficient to represent all the above mentioned operations.
14836519
From Set to Hyperset Unification
In this paper we show how to extend a set unification algorithm— that is, an extended unification algorithm incorporating the axioms of a simple theory of sets—to hyperset unification (roughly speaking, to sets in which membership can form cycles). This result is obtained by enlarging the domain of terms (hence, trees) to that of graphs involving free as well as interpreted function symbols (namely, the set element insertion and the empty set), which can be regarded as a convenient denotation of hypersets. We present a hyperset unification algorithm that (nondeterministically) computes, for each given unification problem, a finite collection of systems of equations in solvable form whose solutions represent a complete set of solutions for the given unification problem. The crucial issue of termination of the algorithm is addressed and solved by the addition of simple nonmembership constraints. Finally, the hyperset unification problem in
707114
Compiling Intensional Sets in CLP
Constructive negation has been proved to be a valid alternative to negation as failure, especially when negation is required to have, in a sense, an ‘active’ role. In this paper we analyze an extension of the original constructive negation in order to gracefully integrate with the management of set-constraints in the context of a Constraint Logic Programming Language dealing with finite sets. We show that the marriage between CLP with sets and constructive negation gives us the possibility of representing a general class of intensionally defined sets without any further extension to the operational semantics of the language. The presence of intensional sets allows a definite increase in the expressive power and abstraction level offered by the host logic language.
1023546
A WAM Implementation for the Logic Meta Programming Language 'Log
A technique for compiling the meta-programming logic programming language 'Log (read quote log) is presented and the extensions to the standard Warren Abstract Machine (WAM) architecture necessary to support the execution of 'Log programs are described. 'Log is a logic programming language upgraded with a flexible naming scheme and a set of operators allowing each syn tactic entity to be referred to and manipulated at the desired detail level. This language still possesses the declarative semantics of pure Prolog. Upgrading the WAM architecture to support 'Log has required to cope with some novel implementation challenges. First, an efficient internal representation for both meta-representations of 'Log must be provided. Second the execution of a 'Log program generates constraints that must be handled dynamically by the run-time architecture of the WAM. A 'Log compiler has been implemented along with a WAM based run-time sup port architecture.