The CUED’s Grammatical Error Correction Systems for BEA-2019
Table 7: Impact of identity removal on Base models.
['[BOLD] Identity  [BOLD] Removal', '[BOLD] CoNLL-2014  [BOLD] P', '[BOLD] CoNLL-2014  [BOLD] R', '[BOLD] CoNLL-2014  [BOLD] M2', '[BOLD] BEA-2019 Dev  [BOLD] P', '[BOLD] BEA-2019 Dev  [BOLD] R', '[BOLD] BEA-2019 Dev  [BOLD] ERR.']
We note that removing these identity mappings can be seen as measure to control the balance between precision and recall. As shown in Tab. It depends on the test set whether this results in an improvement in F0.5 score. For the subsequent experiments we found that removing identities in the parallel training corpora but not in the back-translated synthetic data works well in practice.