Explicit solutions of fractional differential equations with uncertainty

We give the explicit solutions of uncertain fractional differential equations (UFDEs) under Riemann–Liouville H-differentiability using Mittag-Leffler functions. To this end, Riemann–Liouville H-differentiability is introduced which is a direct generalization of the concept of Riemann–Liouville differentiability in deterministic sense to the fuzzy context. Moreover, equivalent integral forms of UFDEs are determined which are applied to derive the explicit solutions. Finally, some illustrative examples are given.     

On the new solutions for a fully fuzzy linear system

In this paper, we propose a new method to present a fuzzy trapezoidal solution, namely “suitable solution”, for a fully fuzzy linear system (FFLS) based on solving two fully interval linear systems (FILSs) that are 1-cut and 0-cut of the related FILS. After some manipulations, two FILSs are transformed to 2n crisp linear equations and 4n crisp linear nonequations and n crisp nonlinear equations. Then, we propose a nonlinear programming problem (NLP) to computing simultaneous (synchronic) equations and nonequations. Moreover, we define two other new solutions namely, “fuzzy surrounding solution” and “fuzzy peripheral solution” for an FFLS. It is shown that the fuzzy surrounding solution is placed in a tolerable fuzzy solution set and the fuzzy peripheral solution is placed in a controllable fuzzy solution set. Finally, some numerical examples are given to illustrate the ability of the proposed methods.     

The Parametric Form of Z‐Number and Its Application in Z‐Number Initial Value Problem

In this paper, the parametric form of Z‐numbers is introduced and it is followed by defining arithmetic operations on them. To suggest Z‐number initial value problem (ZIVP), definition of derivative of Z‐process is necessary. For this purpose, the generalized Hukuhara differentiation and generalized differentiation are defined in details. To solve the mentioned ZIVP, the characterization theorem is proved. Finally, for more illustrations of the subject, some examples are solved and expounded.     

Improved predictor-corrector method for solving fuzzy initial value problems

In this paper, an improved predictor-corrector (IPC) method is proposed to solve the “fuzzy initial value problem”. The IPC method is generated by combining an explicit three-step method and an implicit two-step method. The methods are compared with the methods discussed in [T. Allahviranloo, N. Ahmady, E. Ahmady, Numerical solution of fuzzy differential equations by predictor-corrector method, Information Sciences 177(7) (2007) 1633-1647], and are shown to be more accurate. The convergence and stability of the proposed methods are also presented in detail. These methods are illustrated by solving some examples.     

Two new methods for ranking of Z‐numbers based on sigmoid function and sign method

This paper introduces two processes of ranking methods on Z‐numbers that are effectively able to deal with uncertain decision‐making data. Decision making is based on recommended Z‐ numbers. For this purpose first, the Z‐number is transformed to a fuzzy number and then the ranking method by using the sigmoid function and the sign method is used to mention fuzzy numbers. For the next step, the method is extended to related Z‐numbers. Finally, we use it to prioritize the items and solve some examples.     

The use of airfoil and Chebyshev polynomials methods for solving fuzzy Fredholm integro-differential equations with Cauchy kernel

In this paper the airfoil and the Chebyshev polynomials methods to solve the fuzzy Fredholm integro-differential equation with Cauchy kernel under generalized \(H\) -differentiability are discussed. The existence and uniqueness of the solution and convergence of the proposed methods are proved in details. Finally some examples show the accuracy of these methods.     

A new method for solving an arbitrary fully fuzzy linear system

In this paper, We propose a simple and practical method (that works only for triangular fuzzy numbers) to solve an arbitrary fully fuzzy linear system (FFLS) in the form $\widetilde{A}\otimes \widetilde{x}=\widetilde{b},$ where $\widetilde{A}_{n \times n}$ is a fuzzy matrix, $\widetilde{x}$ and $\widetilde{b}$ are n × 1 fuzzy vectors. The idea of the presented method is constructed based on the extending 0-cut and 1-cut solution of original fully fuzzy linear systems (FFLS). We also define a fuzzy solution of FFLS and establish the necessary and sufficient conditions for the uniqueness of a fuzzy solution.     

A method to find fuzzy eigenvalues and fuzzy eigenvectors of fuzzy matrix

In this paper, the fuzzy eigenvalues and fuzzy eigenvectors of a fuzzy matrix have been found. To do this, the spreads are allocated to the obtained core from the corresponding crisp matrix which it makes a fuzzy number surely.     

Fuzzy Laplace transforms

In this paper we propose a fuzzy Laplace transform and under the strongly generalized differentiability concept, we use it in an analytic solution method for some fuzzy differential equations (FDEs). The related theorems and properties are proved in detail and the method is illustrated by solving some examples.