This is the reference implementation of commonly used coreference metrics.
Clone or download


Reference Coreference Scorer


This is the official implementation of the revised coreference scorer used for CoNLL-2011/2012 shared tasks on coreference resolution. It addresses issues that prevented the consistent scoring of predicted mentions in the past.


The current stable (official) version for scoring predicted mentions is v8.01


We would appreciate if you cite the paper when you use this scorer as some of us are academics or wanting to be academics, and citations matter.

  author    = {Pradhan, Sameer  and  Luo, Xiaoqiang  and  Recasens, Marta  and  Hovy, Eduard  and  Ng, Vincent  and  Strube, Michael},
  title     = {Scoring Coreference Partitions of Predicted Mentions: A Reference Implementation},
  booktitle = {Proceedings of the 52nd Annual Meeting of the Association for Computational Linguistics (Volume 2: Short Papers)},
  month     = {June},
  year      = {2014},
  address   = {Baltimore, Maryland},
  publisher = {Association for Computational Linguistics},
  pages     = {30--35},
  url       = {}


perl <metric> <key> <response> [<document-id>]

<metric>: the metric desired to score the results. one of the following values:

muc: MUCScorer (Vilain et al, 1995)
bcub: B-Cubed (Bagga and Baldwin, 1998)
ceafm: CEAF (Luo et al., 2005) using mention-based similarity
ceafe: CEAF (Luo et al., 2005) using entity-based similarity
blanc: BLANC (Luo et al., 2014) BLANC metric for gold and predicted mentions
all: uses all the metrics to score

<key>: file with expected coreference chains in CoNLL-2011/2012 format

<response>: file with output of coreference system (CoNLL-2011/2012 format)

<document-id>: optional. The name of the document to score. If name is not
               given, all the documents in the dataset will be scored. If given
               name is "none" then all the documents are scored but only total
               results are shown.


The score subroutine returns an array with four values in this order:

Coreference Score

Recall = recall_numerator / recall_denominator
Precision = precision_numerator / precision_denominator
F1 = 2 * Recall * Precision / (Recall + Precision)

These values are to standard output when variable $VERBOSE is not null.

Identification of Mentions

A score for identification of mentions (recall, precision and F1) is also included. Mentions from system response are compared with key mentions. This version performs strict mention matching as was used in the CoNLL-2011 and 2012 shared tasks.


  • Emili Sapena, Universitat Politècnica de Catalunya,, esapena <at>
  • Sameer Pradhan,, pradhan <at>
  • Sebastian Martschat, sebastian.martschat <at>
  • Xiaoqiang Luo, xql <at>


2009-2011, Emili Sapena esapena <at>
2011-      Sameer Pradhan pradhan <at>