Rule-based Software Verification and Correction

Author: Demis Ballis
Title: Rule-based Software Verification and Correction
Language of presentation: Italian
Promotor: Prof. Moreno Falaschi and Prof. María Alpuente
Date of defense: February 2005
Institution granting degree: Universidad Politécnica de Valencia, Spain and Università degli Studi di Udine, Italy


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 top-down 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 also infer semi-automatically 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.

Last Update: March 2005