Transliterated Mobile Keyboard Input via Weighted Finite-State Transducers

We present an extension to a mobile key-board input decoder based on finite-state transducers that provides general translit-eration support, and demonstrate its use for input of South Asian languages using a QWERTY keyboard. On-device keyboard decoders must operate under strict latency and memory constraints, and we present several transducer optimizations that allow for high accuracy decoding under such constraints. Our methods yield substantial accuracy improvements and latency reductions over an existing baseline translit-eration keyboard approach. The resulting system was launched for 22 languages in Google Gboard in the first half of 2017.