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:ALEPHExactL2 : Uses the limited-memory BFGS algorithm (Liu & Nocedal, 1989) implemented in ALCHEMY to learn discriminative MLN weights for the clauses in the final theory returned by ALEPH.
Category: