Failure Transducers and Applications in Knowledge-Based Text Processing

摘要

Finite-state devices encoding lexica and related knowledge bases often become very large. A well-known technique for reducing the size of finite-state automata is the use of failure transitions. Here we generalize the concept of failure transitions for finite-state automata to the case of subsequential transducers. Failure transitions in the new sense do not have input but may produce output. As an application field for failure transducers we consider text rewriting with large rewrite lexica under the leftmost-longest replacement strategy. It is shown that using failure transducers leads to a huge space reduction compared to the use of standard subsequential transducers. As a concrete example we show how all Wikipedia concepts in an input text can be linked in an online manner with the Wikipedia pages of the concepts using failure transducers.