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:We therefore contrast our work with state-of-the-art MI optimization algorithms included in the previously mentioned General Algebraic Modeling System (GAMS) (Bussieck and Meeraus, 2004) commercial algorithm suite as well as the Mixed-Integer Evolution Strategy (MIES) (Li et al., 2013).
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