Résumé  What do you do if a computational object (e.g., a document, a program trace) fails a specification?
An obvious approach is to perform a "repair": modify the object minimally to get something that
satisfies the constraints. This approach has been extensively investigated in the database community
for relational integrity constraints, and in the AI community for propositional logics. Different modification
operators have been considered on the basis of the application scenarios. For instance, a repair of an
XML document usually consists of applying to the underlying tree structure a certain number of editing
operations such as relabelings, deletions, and insertions of nodes.
In this talk I will survey some results related to the worstcase cost of repairing documents between
regular specifications. Precisely, I will focus on the number of edits that are needed to get from a
document (i.e., a word or a tree) that satisfies a source specification (i.e., a regular language S) to
some document that satisfies a target specification (i.e., a regular language T). As this number may
well be unbounded, I will consider the problem of determining those pairs of languages (S,T) such
that one can get from any word/tree in S to a word/tree in T using a finite, uniformly bounded number
of editing operations. I will give effective characterizations of these pairs when S and T are given by
finite state automata (word case) or stepwise tree automata (tree case), and derive some complexity
bounds for the corresponding problems.
The presentation is based on joint works with Michael Benedikt, Cristian Riveros, and Sławek Staworko.
