We introduce an automata-theoretic approach for the verification of multi-agent systems. We present a translation between branching time temporal-epistemic logic and alternating tree automata. Model checking an interpreted system against a temporal-epistemic formula is reduced to checking the non-emptiness of the composition of two tree automata. We exemplify this technique using a simple multi...

A new kind of an acyclic pushdown automaton for an ordered tree is presented. The nonlinear tree pattern pushdown automaton represents a complete index of the tree for nonlinear tree patterns and accepts all nonlinear tree patterns which match the tree. Given a tree with n nodes, the number of such nonlinear tree patterns is O((2+ v)n), where v is the number of variables in the patterns. We dis...

In this master thesis project a class of tree grammars called “Branching tree grammar” has been implemented into the TREEBAG system. A tree grammar is a device that generates a language of mathematical trees, according to rules specified by the user. These trees can then be transformed into for example pictures, by other components in TREEBAG. The branching tree grammar, which is a class of gra...

Stay macro tree transducers (smtts) are an expressive formalism for reasoning about XSLT-like document transformations. Here, we consider the exact type checking problem for smtts. While the problem is decidable, the involved technique of inverse type inference is known to have exponential worst-case complexity (already for top-down transformations without parameters). We present a new adaptive...

Containment of monadic datalog programs over data trees (labelled trees with an equivalence relation) is undecidable. Recently, decidability was shown for two incomparable fragments: downward programs, which never move up from visited tree nodes, and linear childonly programs, which have at most one intensional predicate per rule and do not use descendant relation. As di erent as the fragments ...

This paper tackles the problem of the existence of solutions for recursive systems of Horn clauses with second-order variables interpreted as integer relations, and harnessed by quantifier-free difference bounds arithmetic. We start by proving the decidability of the problem ”does the system have a solution ?” for a simple class of Horn systems with one second-order variable and one non-linear ...

This paper generalizes the notion of a strong LL(k) context-free grammar for the case of conjunctive grammars and develops a top-down parsing algorithm for the resulting language family. A top-down parser of a conjunctive language attempts to construct a derivation of the input string, at each step using a nite lookahead to determine which grammar rule to apply. Fragments of formulae that form ...

We introduce a weighted tree transducer model that combines aspects of weighted top down tree transducers and monadic datalog; this allows us to specify information transport for non-adjacent nodes in a single rule. We will investigate four different semantics for our weighted tree transducer model and prove that they coincide under certain conditions. We present and prove the correctness of an...

Context-free S grammars are introduced, for arbitrary (storage) type S, as a uniform framework for recursion-based grammars, automata, and transducers, viewed as programs. To each occurrence of a nonterminal of a context-free S grammar an object of type S is associated, that can be acted upon by tests and operations, as indicated in the rules of the grammar. Taking particular storage types give...

In this paper we lift the result of Hashiguchi of decidability of the restricted star-height problem for words to the level of finite trees. Formally, we show that it is decidable, given a regular tree language L and a natural number k whether L can be described by a disjunctive μ-calculus formula with at most k nesting of fixpoints. We show the same result for disjunctive μ-formulas allowing s...