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There exist several approaches to rough set approximations in a multigranulation space,namely,a family of equivalence relations.In this paper,we propose a unified framework to classify and compare existing studies.An underlying principle is to explain rough sets in a multigranulation space through rough sets derived by using individual equivalence relations.Two basic models are suggested.One model is based on a combination of a family of equivalence relations into an equivalence relation and the construction of approximations with respect to the combined relation.By combining equivalence relations through set intersection and union,respectively,we construct two sub-models.The other model is based on the construction of a family of approximations from a set of equivalence relations and a combination of the family of approximations.By using set intersection and union to combine a family of approximations,respectively,we again build two sub-models.As a result,we have a total of four models.We examine these models and give conditions under which some of them become the same.