Pynini: A Python library for weighted finite-state grammar compilation


We present Pynini, an open-source library allowing users to compile weighted finite-state transducers (FSTs) and pushdown transducers from strings, context-dependent rewrite rules, and recursive transition networks. Pynini uses the OpenFst library for encoding, modifying, and applying WFSTs, as well as a powerful generic optimization routine. We describe the design of this library and the algorithms and interfaces used for FST and PDT compilation and optimization, and illustrate its use for a natural language processing application.