Multilingual task-oriented dialogue (ToD) facilitates access to services and
information for many (communities of) speakers. Nevertheless, the potential of
this technology is not fully realised, as current datasets for multilingual ToD
- both for modular and end-to-end modelling - suffer from severe limitations.
- When created from scratch, they are usually small in scale and fail to cover
many possible dialogue flows. 2) Translation-based ToD datasets might lack
naturalness and cultural specificity in the target language. In this work, to
tackle these limitations we propose a novel outline-based annotation process
for multilingual ToD datasets, where domain-specific abstract schemata of
dialogue are mapped into natural language outlines. These in turn guide the
target language annotators in writing a dialogue by providing instructions
about each turn’s intents and slots. Through this process we annotate a new
large-scale dataset for training and evaluation of multilingual and
cross-lingual ToD systems. Our Cross-lingual Outline-based Dialogue dataset
(termed COD) enables natural language understanding, dialogue state tracking,
and end-to-end dialogue modelling and evaluation in 4 diverse languages:
Arabic, Indonesian, Russian, and Kiswahili. Qualitative and quantitative
analyses of COD versus an equivalent translation-based dataset demonstrate
improvements in data quality, unlocked by the outline-based approach. Finally,
we benchmark a series of state-of-the-art systems for cross-lingual ToD,
setting reference scores for future work and demonstrating that COD prevents
over-inflated performance, typically met with prior translation-based ToD
datasets.