Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:…role in many NLP applications, deterministic models based on rich sets of expert rules for coreference have been shown recently to achieve performance rivaling, if not exceeding, the performance of state of the art machine learning approaches (Haghighi and Klein, 2009; Raghunathan et al., 2010).
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