  Simultaneous machine translation attempts to translate a source sentence
before it is finished being spoken, with applications to translation of spoken
language for live streaming and conversation. Since simultaneous systems trade
quality to reduce latency, having an effective and interpretable latency metric
is crucial. We introduce a variant of the recently proposed Average Lagging
(AL) metric, which we call Differentiable Average Lagging (DAL). It
distinguishes itself by being differentiable and internally consistent to its
underlying mathematical model.
