In this paper, we obtain the general solution and the generalized Hyers-Ulam Rassias stability of the functional equation 3(f(x+ 2y) + f(x− 2y)) = 12(f(x + y) + f(x− y)) + 4f(3y)− 18f(2y) + 36f(y)− 18f(x).

In this paper a very general matrix quadratic equation is considered. This equation is known in literature as asymmetric Algebraic Riccati Equation (ARE) and arises in the solution of many problems in system and control theory and applied mathematics. For this reason a large amount of work has been produced on this topic. We present a new parametrization of the set of solutions of such equation...

and Applied Analysis 3 for some natural number n0. Moreover, if the second alternative holds, then i the sequence {Jnx} is convergent to a fixed point y∗ of J ; ii y∗ is the unique fixed point of J in the set Y : {y ∈ X | d J0x, y < ∞} and d y, y∗ ≤ 1/ 1 − L d y, Jy , for all , x, y ∈ Y . Following 30, 31 , we recall some basic facts concerning multi-normed spaces and some preliminary results. ...

Sometime in modeling applied problems there may be a degree of uncertainty in the parameters used in the model or some measurements may be imprecise. Due to such features, we are tempted to consider the study of functional equations in the fuzzy setting. The notion of fuzzy sets was first introduced by Zadeh [31] in 1965 which is a powerful hand set for modeling uncertainty and vagueness in var...

The stability problem of functional equations is originated from a question of Ulam 1 concerning the stability of group homomorphisms. Hyers 2 gave a first affirmative partial answer to the question of Ulam for Banach spaces. Hyers’ Theorem was generalized by Aoki 3 for additive mappings and by Th. M. Rassias 4 for linear mappings by considering an unbounded Cauchy difference. The paper of Th. ...

Katsaras 1 defined a fuzzy norm on a vector space to construct a fuzzy vector topological structure on the space. Some mathematicians have defined fuzzy norms on a vector space from various points of view 2–4 . In particular, Bag and Samanta 5 , following Cheng and Mordeson 6 , gave an idea of fuzzy norm in such a manner that the corresponding fuzzy metric is of Kramosil and Michálek type 7 . T...

In any dimension [Formula: see text], for given mass text] and when the energy functional is coercive on constraint we are interested in searching constrained critical points at positive levels. Under general conditions suitable ranges of mass, manage to construct such which appear as a local minimizer or correspond mountain pass symmetric level. particular, our results shed some light cubic–qu...

1 Department of Mathematics, School of Science, Beijing Institute of Technology, Beijing 100081, China 2 Pedagogical Department E.E., Section of Mathematics and Informatics, National and Kapodistrian University of Athens, 4, Agamemnonos Str., Aghia Paraskevi, 15342 Athens, Greece 3 School of Communication and Information Engineering, University of Electronic Science and Technology of China, Che...

In this paper, we obtain the general solution and the stability result for the following functional equation in random normed spaces (in the sense of Sherstnev) under arbitrary t-norms f(x + 3y) + f(x− 3y) = 9(f(x + y) + f(x− y))− 16f(x).