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:Drawing upon previous goal recognition research, (Blaylock and Allen 2003; Mott et al. 2006), the work presented in this chapter defines goal recognition as the task of predicting the most likely goal for a given sequence of observed low-level player behavior in the game environment.
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