In program synthesis, we transform a specification into a system that is guaranteed to satisfy the specification. When the system is open, then at each moment it reads input signals and writes output signals, which depend on the input signals and the history of the computation so far. The specification considers all possible input sequences. Thus, if the specification is linear, it should hold ...

The tree width of an alternating finite automaton (AFA) measures the parallelism in all computations AFA on a given input. maximal existential (respectively, universal) A string w number choices parallel universal branches) one computation w. We give polynomial time algorithms deciding finiteness AFA’s and width. Also we algorithm that for with decides whether or not is finite. Finiteness decid...

Abstract We show the decidability of finite sequentiality problem for unambiguous max-plus tree automata. A automaton is called if there at most one accepting run on every tree. The asks whether a given automaton, exist finitely many deterministic automata whose pointwise maximum equivalent to automaton.

This thesis is focused on techniques for finite automata and their use in practice, with the main emphasis on nondeterministic tree automata. This concerns namely techniques for size reduction and language inclusion testing, which are two problems that are crucial for many applications of tree automata. For size reduction of tree automata, we adapt the simulation quotient technique that is well...

Previous work reports about SXSI, a fast XPath engine which executes tree automata over compressed XML indexes. Here, reasons are investigated why SXSI is so fast. It is shown that tree automata can be used as a general framework for fine grained XML query optimization. We define the “relevant nodes” of a query as those nodes that a minimal automaton must touch in order to answer the query. Thi...

A one-counter automaton is a pushdown automaton with a singleton stack alphabet, where stack emptiness can be tested; it is a real-time automaton if it contains no ε-transitions. We study the computational complexity of the problems of equivalence and regularity (i.e. semantic finiteness) on real-time one-counter automata. The first main result shows PSPACE-completeness of bisimulation equivale...

Nested words provide a natural model of runs of programs with recursive procedure calls. The usual connection between monadic second-order logic (MSO) and automata extends from words to nested words and gives us a natural notion of regular languages of nested words. In this paper we look at some well-known aspects of regular languages – their characterization via fixed points, deterministic and...

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...

Alternating automata play a key role in the automata-theoretic approach to specification, verification, and synthesis of reactive systems. Many algorithms on alternating automata, and in particular, their nonemptiness test, involve removal of alternation: a translation of the alternating automaton to an equivalent nondeterministic one. For alternating Büchi automata, the best known translation ...

A pushdown system is a graph G(P ) of configurations of a pushdown automaton P . The model checking problem for a logic L is: given a pushdown automaton P and a formula α ∈ L decide if α holds in the vertex of G(P ) which is the initial configuration of P . Computation Tree Logic (CTL) and its fragment EF are considered. The model checking problems for CTL and EF are shown to be EXPTIME-complet...