Most research on bilevel linear programming problem  is focused on its deterministic form, in which the coefficients and decision variables in the objective functions and constraints are assumed to be crisp. In fact, due to inaccurate information, it is difficult to know exactly values of coefficients that used to construct a bilevel model. The interval set theory is suitable for describing and...

The main goal of this work is to determine which entire functions preserve nonnegativity of matrices of a fixed order n— i.e., to characterize entire functions f with the property that f(A) is entrywise nonnegative for every entrywise nonnegative matrix A of size n×n. Towards this goal, we present a complete characterization of functions preserving nonnegativity of (block) uppertriangular matri...

Matrix functions preserving several sets of generalized nonnegative matrices are characterized. These sets include PFn, the set of n×n real eventually positive matrices; and WPFn, the set of matrices A ∈ R such that A and its transpose have the Perron-Frobenius property. Necessary conditions and sufficient conditions for a matrix function to preserve the set of n× n real eventually nonnegative ...

in this paper, for a complete lattice l, we introduce interval-valued l-fuzzy ideal (prime ideal) of a near-ring which is an extended notion of fuzzy ideal (prime ideal) of a near-ring. some characterization and properties are discussed.