In this paper, we define a new kind of weighted tree automata where the weights are only supported by final states. We show that these automata are sequentializable and we study their closures under classical regular and algebraic operations. We then use these automata to compute the subtree kernel of two finite tree languages in an efficient way. Finally, we present some perspectives involving...

We study cellular automata on regular rooted trees. This includes the characterization of sofic tree shifts in terms of unrestricted Rabin automata and the decidability of the surjectivity problem for cellular automata between sofic tree shifts.

This paper provides an algorithm to compute the complement of tree languages recognizable with A-TA (tree automata with associativity axioms [16]). Due to this closure property together with the previously obtained results, we know that the class is boolean closed, while keeping recognizability of A-closures of regular tree languages. In the proof of the main result, a new framework of tree aut...

We present an efficient algorithm to reduce the size of nondeterministic tree automata, while retaining their language. It is based on new transition pruning techniques, and quotienting of the state space w.r.t. suitable equivalences. It uses criteria based on combinations of downward and upward simulation preorder on trees, and the more general downward and upward language inclusions. Since tr...

We consider the representational state complexity of unranked tree automata. The bottomup computation of an unranked tree automaton may be either deterministic or nondeterministic, and further variants arise depending on whether the horizontal string languages defining the transitions are represented by a DFA or an NFA. Also, we consider for unranked tree automata the alternative syntactic defi...

This paper presents new classes of tree automata combining automata with equality test and automata modulo equational theories. We believe that this class has a good potential for application in e.g. software verification. These tree automata are obtained by extending the standard Horn clause representations with equational conditions and rewrite systems. We show in particular that a generalize...

The aim of this thesis is to provide verification techniques based on formal language theory and graph theory for graph transformation systems. Graph transformation systems can be used in a large number of application areas. In many cases it is very natural to model concurrent and distributed systems or other systems, where evolving graph-like structures play a role, by means of graph transform...

We improve on an existing [P.A. Abdulla, J. Högberg, L. Kaati. Bisimulation Minimization of Tree Automata. Int. J. Found. Comput. Sci. 18(4): 699–713, 2007] bisimulation minimization algorithm for finite-state tree automata by introducing backward and forward bisimulation and developing minimization algorithms for them. Minimization via forward bisimulation is also effective on deterministic tr...