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Reverse supply chain is a process dealing with the backward flows of used/damaged products or materials. Reverse supply chain includes activities such as collection, inspection, reprocess, disposal and redistribution. A well-organized reverse supply chain can provide important advantages such as economic and environmental ones. In this study, we propose a general framework and formulate a mathematical model for product return in reverse supply chain. We consider a multilayer, multi-product for the model. The main objective of the paper is minimizing the total costs of reverse supply chain including transportation, fixed opening, operation, maintenance and remanufacturing costs of centers. To validate the mathematical model, a numerical example is solved using Lingo 9 software and the results are reported. Keywords: Reverse Supply Chain, Product Return, Mathematical Model.

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Modeling and solving real world problems is one of the most important issues in optimization problems. In this paper, we present an approach to solve Fuzzy Interval Flexible Linear Programming (FIFLP) problems that simultaneously have the interval ambiguity in the matrix of coefficients .In the first step, using the interval problem solving techniques; we transform the fuzzy interval flexible problem into two optimistic and pessimistic sub-problems. Then, in the second step, using a multi-parametric approach, we solve two fuzzy flexible sub- problems and finally the results are investigated with numerical example.