fuzzy linear regression models are used to obtain an appropriate linear relation between a dependent variable and several independent variables in a fuzzy environment. several methods for evaluating fuzzy coefficients in linear regression models have been proposed. the first attempts at estimating the parameters of a fuzzy regression model used mathematical programming methods. in this the...

In this paper, the problem of proportional covariance matrices estimation for random Gaussian complex vectors is investigated. The maximum likelihood estimates of the matrix and the scale factors are derived, and their statistical performances are studied, through bias, consistency and asymptotic distribution. It is also shown that the problem treated here generalizes the covariance estimation ...

for the polynomial planar vector fields with a hyperbolic or nilpotent critical point at the origin, the monodromy problem has been solved, but for the strongly degenerate critical points this problem is still open. when the critical point is monodromic, the stability problem or the center- focus problem is an open problem too. in this paper we will consider the polynomial planar vector fields ...