  The PDTB-3 contains many more Implicit discourse relations than the previous
PDTB-2. This is in part because implicit relations have now been annotated
within sentences as well as between them. In addition, some now co-occur with
explicit discourse relations, instead of standing on their own. Here we show
that while this can complicate the problem of identifying the location of
implicit discourse relations, it can in turn simplify the problem of
identifying their senses. We present data to support this claim, as well as
methods that can serve as a non-trivial baseline for future state-of-the-art
recognizers for implicit discourse relations.
