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:Similarly, recent work by Balcan, Beygelzimer and Langford [2] provides an upper bound on label-complexity of Õ(d2 log 1 ) for learning half-spaces under the uniform, in a certain agnostic scenario, via an intractable algorithm.
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