Rule-Based Software Verification and Correction.

Abstract

The increasing complexity of software systems has led to the development of sophisticated formal methodologies for verifying and correcting data and programs. In general, establishing whether a program behaves correctly w.r.t. the original programmer's intention or checking the consistency and the correctness of a large set of data are not trivial tasks as witnessed by many case studies which occur in the literature.In this dissertation, we face two challenging problems of verification and correction. Specifically, the verification and correction of declarative programs, and the verification and correction of Web sites (i.e. large collections of semistructured data).Firstly, we propose a general correction scheme for automatically correcting declarative, rule-based programs which exploits a combination of bottom-up as well as topdown inductive learning techniques. Our hybrid methodology is able to infer program corrections that are hard, or even impossible, to obtain with a simpler, automatic top-down or bottom-up learner. Moreover, the scheme will be also particularized to some well-known declarative programming paradigm: that is, the functional logic and the functional programming paradigm.Secondly, we formalize a framework for the automated verification of Web sites which can be used to specify integrity conditions for a given Web site, and then automatically check whether these conditions are fulfilled. We provide a rule-based, formal specification language which allows us to define syntactic as well as semantic properties of the Web site. Then, we formalize a verification technique which detects both incorrect/forbidden patterns as well as lack of information, that is, incomplete/missing Web pages. Useful information is gathered during the verification process which can be used to repair the Web site. So, after a verification phase, one can semi-automatically infer some possible corrections in order to fix the Web site. The methodology is based on a novel rewriting-like technique, called partial rewriting, in which the traditional pattern matching mechanism is replaced by a more suitable technique (tree simulation) for recognizing patterns inside semistructured documents. SommarioLa crescente complessità dei sistemi software ha reso necessario lo sviluppo di sofisticate metodologie formali per la verifica e la correzione di dati e programmi. In generale, stabilire se un programma si comporta correttamente rispetto alle intenzioni originali del programmatore o controllare la consistenza e la correttezza di grandi insiemi di dati non sono compiti triviali, comeè testimoniato dai numerosi casi di studio presenti in letteratura.In questa tesi affrontiamo due interessanti problemi di verifica e correzione: la verifica e correzione di programmi dichiarativi e la verifica e correzione di siti Web (i.e. collezioni di dati semistrutturati).In primo luogo, proponiamo uno schema generale per la correzione automatica di programmi dichiarativi rule-based, il quale sfrutta una combinazione di tecniche di inductiv...

Specialization of Recursive Predicates from Positive Examples Only

“…A bottom-up approach has been proposed in (Kanamori and Seki, 1986;Ferri et al, 2001;Leuschel and Massart, 2003). Ballis (2005) claimed that his approach can be applied as a top down or a bottom up approach. All those approaches are driven by (a finite set) positive and negative examples.…”

“…The framework presented here has two major advantages: (i) The positive examples defined in E + are guaranteed to be included both in the meaning of the original program and of the specialized version. Note that in (Ballis, 2005;Alpuente et al, 2001;Bostrom and Idestam-Almquist, 1999), E + consists of a finite set of ground atoms and it is not clear how they handle cases when some positive examples are not included in the original program. (ii) The specialization process is performed according to the positive examples only, no need to negative examples.…”