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:To train the model, we optimize cross-entropy loss with stochastic gradient descent using minibatched backpropagation through time (BPTT; Rumelhart et al., 1988; Mikolov, 2012); the minibatch size for BPTT, again tuned on the dev set, is set to 9.
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