Internal rate of return of investment projects with fuzzy interactive payments

The internal rate of return of a fuzzy cash flow can be naturally presented as a solution of an algebraic equation with fuzzy coefficients. In this paper we construct fuzzy rate of return using the extension principle. We give an analog of the Norstrom condition providing the existence of a unique internal rate of return. To take into account the interaction of payments, we consider addition of fuzzy quantities with respect to triangular norms.