Synchronous tree substitution grammars (stsg) are a (formal) tree transformation model that is used in the area of syntax-based machine translation. A competitor that is at least as expressive as stsg is proposed and compared to stsg. The competitor is the extended multi bottom-up tree transducer (mbot), which is the bottom-up analogue with the additional feature that states have non-unary ranks. Unweighted mbot have already been investigated with respect to their basic properties, but the particular properties of the constructions that are required in the machine translation task are largely unknown. stsg and mbot are compared with respect to binarization, regular restriction, and application. Particular attention is paid to the complexity of the constructions.

In this paper, we present techniques that exploit finite-state models for voice search applications. In particular, we illustrate the use of finite-state models for encoding the search index in order to tightly integrate the speech recognition and the search components of a voice search system. We show that the tight integration mutually benefits Automatic Speech Recognition and improves the search. In the second part of the paper, we discuss the use of finite-state techniques for spoken language understanding, in particular, to segment an input query into its component semantic fields so as to improve search as well as to extend the functionality of the system and be able to execute the user's request against a backend database.

Text correction systems rely on a core mechanism where suitable correction suggestions for garbled input tokens are generated. Current systems, which are designed for documents including modern language, use some form of approximate search in a given background lexicon. Due to the large amount of spelling variation found in historical documents, special lexica for historical language can only offer restricted coverage. Hence historical language is often described in terms of a matching procedure to be applied to modern words. Given such a procedure and a base lexicon of modern words, the question arises of how to generate correction suggestions for garbled historical variants. In this paper we suggest an efficient algorithm that solves this problem. The algorithm is used for postcorrection of optical character recognition results on historical document collections.