Head automata for speech translation

Presents statistical language and translation models based on collections of small finite-state machines that we call "head automata". The models are intended to capture the lexical sensitivity of N-gram models and direct statistical translation models, while at the same time taking account of the hierarchical phrasal structure of language. Two types of head automata are defined: relational head automata, which are suitable for translation by the transfer of dependency trees, and head transducers, which are suitable for direct recursive lexical translation.