CLaC at SemEval-2023 Task 2: Comparing Span-Prediction and
  Sequence-Labeling approaches for NER
Harsh Verma Sabine Bergler
This paper summarizes the CLaC submission for the MultiCoNER 2 task which
concerns the recognition of complex, fine-grained named entities. We compare
two popular approaches for NER, namely Sequence Labeling and Span Prediction.
We find that our best Span Prediction system performs slightly better than our
best Sequence Labeling system on test data. Moreover, we find that using the
larger version of XLM RoBERTa significantly improves performance.
Post-competition experiments show that Span Prediction and Sequence Labeling
approaches improve when they use special input tokens (<s> and </s>) of
XLM-RoBERTa. The code for training all models, preprocessing, and
post-processing is available at
https://github.com/harshshredding/semeval2023-multiconer-paper.