  Scientific claim verification is a unique challenge that is attracting
increasing interest. The SCIVER shared task offers a benchmark scenario to test
and compare claim verification approaches by participating teams and consists
in three steps: relevant abstract selection, rationale selection and label
prediction. In this paper, we present team QMUL-SDS's participation in the
shared task. We propose an approach that performs scientific claim verification
by doing binary classifications step-by-step. We trained a BioBERT-large
classifier to select abstracts based on pairwise relevance assessments for each
<claim, title of the abstract> and continued to train it to select rationales
out of each retrieved abstract based on <claim, sentence>. We then propose a
two-step setting for label prediction, i.e. first predicting "NOT_ENOUGH_INFO"
or "ENOUGH_INFO", then label those marked as "ENOUGH_INFO" as either "SUPPORT"
or "CONTRADICT". Compared to the baseline system, we achieve substantial
improvements on the dev set. As a result, our team is the No. 4 team on the
leaderboard.
