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 ...

The output distribution formula for stack filters based on mirrored threshold decomposition is derived. This formula allows one to compute the cumulative distribution function of the output of a stack filter for a given independent and identically distributed (i.i.d.) input noise distribution. Mirrored threshold decomposition permits us to analyze the input–output characteristics of the stack f...

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...

This work describes an approach for inferring De-terministic Context-free (DCF) Grammars in a Connectionist paradigm using a Recurrent Neu-ral Network Pushdown Automaton (NNPDA). The NNPDA consists of a recurrent neural network connected to an external stack memory through a common error function. We show that the NNPDA is able to learn the dynamics of an underlying push-down automaton from exa...

We introduce timed alternating tree automata as a natural extension of timed automata for the purpose of solving the model checking problem for timed computation tree logic (TCTL) following the automata-theoretic approach. This settles a problem posed by Hen-zinger, Kupferman, and Vardi. With their pioneering work in the late fties and early sixties, BBchi, Rabin, Trakhtenbrot and others demons...

We develop an automata-theoretic framework for reasoning about infinitestate sequential systems. Our framework is based on the observation that states of such systems, which carry a finite but unbounded amount of information, can be viewed as nodes in an infinite tree, and transitions between states can be simulated by finite-state automata. Checking that the system satisfies a temporal propert...

Fixpoint expressions built from functional signatures interpreted over arbitrary complete lattices are considered. A generic notion of automaton is defined and shown, by means of a tableau technique, to capture the expressive power of fixpoint expressions. For interpretation over continuous and complete lattices, when, moreover, the meet symbol ^ commutes in a rough sense with all other functio...

This paper presents a composition method for stack-attributed tree transducers. Stackattributed tree transducers extend attributed tree transducers with a pushdown stack device for attribute values. Stack-attributed tree transducers are more powerful than attributed tree transducers due to the stack mechanism. We extend the existing composition method for attributed tree transducers to the comp...