Introduction A classical question in the theory of functional equations is “when is it true that a mapping, which approximately satisfies a functional equation, must be somehow close to an exact solution of the equation?”. Such a problem, called a stability problem of the functional equation, was formulated by Ulam [1] in 1940. In the next year, Hyers [2] gave a partial solution of Ulam’s probl...

In 1940, Ulam 1 gave a talk before the Mathematics Club of the University of Wisconsin in which he discussed a number of unsolved problems, containing the stability problem of homomorphisms as follows Let G1 be a group and let G2 be a metric group with the metric d ·, · . Given ε > 0, does there exist a δ > 0 such that if a mapping h : G1 → G2 satisfies the inequality d h xy , h x h y < δ for a...

The stability problem of the functional equation was conjectured by Ulam 1 during the conference in the University of Wisconsin in 1940. In the next year, it was solved by Hyers 2 in the case of additive mapping, which is called the Hyers-Ulam stability. Thereafter, this problem was improved by Bourgin 3 , Aoki 4 , Rassias 5 , Ger 6 , and Gǎvruţa et al. 7, 8 in which Rassias’ result is called t...

In 1941 D.H. Hyers solved the well-known Ulam stability problem for linear mappings. In 1951 D.G. Bourgin was the second author to treat the Ulam problem for additive mappings. In 1982–2005 we established the Hyers–Ulam stability for the Ulam problem of linear and nonlinear mappings. In 1998 S.-M. Jung and in 2002–2005 the authors of this paper investigated the Hyers–Ulam stability of additive ...

In this work, by considering a class of matrix valued fuzzy controllers and using (?,?)-Cauchy–Jensen additive functional equation ((?,?)-CJAFE), we apply the Radu–Mihet method (RMM), which is derived from an alternative fixed point theorem, obtain existence unique solution H–U–R stability (Hyers–Ulam–Rassias) for homomorphisms Jordan on Lie algebras with ? members (?-LMVFA). With regards to ea...

Hyers-Ulam-Rassias stability have been studied in the contexts of several areas of mathematics. The concept of fuzziness and its extensions have been introduced to almost all branches of mathematics in recent times.Here we define the cubic functional equation in 2-variables and establish that Hyers-Ulam-Rassias stability holds for such equations in intuitionistic fuzzy Banach spaces.

In this paper, we investigate the generalized Hyers Ulam Rassias stability of a new quadratic functional equation f(2x + y) + f(2x− y) = 2f(x + y) + 2f(x− y) + 4f(x)− 2f(y). Generalized Hyers-Ulam-Rassias Stability K. Ravi, R. Murali and M. Arunkumar vol. 9, iss. 1, art. 20, 2008 Title Page

We provide three large classes of control functions that ensure the hyperstability Cauchy equation on restricted domains included in various types commutative semigroups. Among other consequences, we obtain significant improvements similar results known from literature for several Aoki-Rassias-type functions.