We present a method for inducing new dialogue systems from very small amounts
of unannotated dialogue data, showing how word-level exploration using
Reinforcement Learning (RL), combined with an incremental and semantic grammar
- Dynamic Syntax (DS) - allows systems to discover, generate, and understand
many new dialogue variants. The method avoids the use of expensive and
time-consuming dialogue act annotations, and supports more natural
(incremental) dialogues than turn-based systems. Here, language generation and
dialogue management are treated as a joint decision/optimisation problem, and
the MDP model for RL is constructed automatically. With an implemented system,
we show that this method enables a wide range of dialogue variations to be
automatically captured, even when the system is trained from only a single
dialogue. The variants include question-answer pairs, over- and
under-answering, self- and other-corrections, clarification interaction,
split-utterances, and ellipsis. This generalisation property results from the
structural knowledge and constraints present within the DS grammar, and
highlights some limitations of recent systems built using machine learning
techniques only.