  Commonsense reasoning is omnipresent in human communications and thus is an
important feature for open-domain dialogue systems. However, evaluating
commonsense in dialogue systems is still an open challenge. We take the first
step by focusing on event commonsense that considers events and their
relations, and is crucial in both dialogues and general commonsense reasoning.
We propose ACCENT, an event commonsense evaluation metric empowered by
commonsense knowledge bases (CSKBs). ACCENT first extracts event-relation
tuples from a dialogue, and then evaluates the response by scoring the tuples
in terms of their compatibility with the CSKB. To evaluate ACCENT, we construct
the first public event commonsense evaluation dataset for open-domain
dialogues. Our experiments show that ACCENT is an efficient metric for event
commonsense evaluation, which achieves higher correlations with human judgments
than existing baselines.
