Linear-Time Recognizable Classes of Tree Languages by Deterministic Linear Pushdown Tree Automata

Restarting Tree Automata and Linear Context-Free Tree Languages

A linear time extension of deterministic pushdown automata

A linear time extension of deterministic pushdown automata is introduced that recognizes all deterministic context-free languages, but also languages such as {abc | n ≥ 0} and the MIX language. It is argued that this new class of automata, called λ-acyclic read-first deterministic stack+bag pushdown automata, has applications in natural language processing.

Branching Pushdown Tree Automata

We observe that pushdown tree automata (PTAs) known in the literature cannot express combinations of branching and pushdown properties. This is because a PTA processes the children of a tree node in possibly different control states but with identical stacks. We propose branching pushdown tree automata (BPTAs) as a solution. In a BPTA, a push-move views its matching pops as an unbounded, unorde...

Tree Automata and Automata on Linear Orderings

We show that the inclusion problem is decidable for rational languages of words indexed by scattered countable linear orderings. The method leans on a reduction to the decidability of the monadic second order theory of the infinite binary tree [9]. Mathematics Subject Classification. 68Q45, 03D05.

Nonlinear Tree Pattern Pushdown Automata

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...