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 {a n b n c n | n ≥ 0} and the MIX language. It is argued that this new class of automata, called -acyclic read-first deterministic stack+bag pushdown automata, has applications in natural language processing.