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:Computational problems that are susceptible of being solved by sensor fields can be stated in the following way [2]: Sensing Problem Π: Given an n-tuple of data streams u = (uk)1≤k≤n for some n ≥ 1, compute an m-tuple of data streams v = (vk)1≤k≤m for some m ≤ n such that RΠ(u[1, t],v[1, t]) is satisfied for every t ≥ 1.
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