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:…seeks to infer agents’ goals along with their plans for achieving them from sequences of observable actions, has been studied for tasks ranging from traffic monitoring (Pynadath and Wellman 2000) to operating system usage (Blaylock and Allen 2003) to story understanding (Charniak and Goldman 1993).
Category: