We prove a general stability theorem of an n-dimensional quadratic-additive type functional equation [Formula: see text]by applying the direct method.

We revise a previous result about the Fr\"ohlich dynamics in strong coupling limit obtained [Gri17]. In latter it was shown that time evolution applied to initial state $\varphi_0 \otimes \xi_\alpha$, where $\varphi_0$ is electron ground of Pekar energy functional and $\xi_\alpha$ associated coherent phonons, can be approximated by global phase for times small compared $\alpha^2$. present note ...

In this paper, we prove the generalized Hyers–Ulam stability of a quadratic and quartic functional equation in intuitionistic fuzzy Banach spaces.

In this paper, a numerical method is proposed for solving optimal control problem of Volterra integral equations using radial basis functions (RBFs) for approximating unknown function. Actually, the method is based on interpolation by radial basis functions including multiquadrics (MQs), to determine the control vector and the corresponding state vector in linear dynamic system while minimizing...

In this paper, we determine some stability results concerning the 2-dimensional vector variable quadratic functional equation f(x+ y, z + w) + f(x − y, z − w) = 2f(x, z) + 2f(y, w) in intuitionistic fuzzy normed spaces (IFNS). We define the intuitionistic fuzzy continuity of the 2-dimensional vector variable quadratic mappings and prove that the existence of a solution for any approximately 2-d...

the study of stability problems of functional equations was motivated by a question of s.m. ulam asked in 1940. the first result giving answer to this question is due to d.h. hyers. subsequently, his result was extended and generalized in several ways.we prove some hyperstability results for the equation g(ax+by)+g(cx+dy)=ag(x)+bg(y)on restricted domain. namely, we show, under some weak natural...

Let Sr be the blow-up of P 2 in r general points, i.e., a smooth Del Pezzo surface of degree 9 − r. For r ≤ 7, we determine the quadratic equations defining its Cox ring explicitly. The ideal of the relations in Cox(S8) is calculated up to radical. As conjectured by Batyrev and Popov, all the generating relations are quadratic.

The type II1 unprojection is, by definition, the generic complete intersection type II unprojection, in the sense of [P] Section 3.1, for the parameter value k = 1, and depends on a parameter n ≥ 2. Our main results are the explicit calculation of the linear relations of the type II1 unprojection for any value n ≥ 2 (Theorem 3.16) and the explicit calculation of the quadratic equation for the c...

1 Department of Mathematics, Islamic Azad University-Ayatollah Amoli Branch, Amol, P.O. Box 678, Iran 2 Department of Mathematics Education and the RINS, Gyeongsang National University, Chinju 660-701, South Korea 3 Department of Mathematics, Research Institute for Natural Sciences, Hanyang University, Seoul 133-791, South Korea 4 Dipartimento di Matematica ed Applicazioni, Università degli Stu...

Let X,Y be complex vector spaces. Recently, Park and Th.M. Rassias showed that if a mapping f : X → Y satisfies f(x+ iy) + f(x− iy) = 2f(x)− 2f(y) (1) for all x, y ∈ X, then the mapping f : X → Y satisfies f(x+ y) + f(x− y) = 2f(x) + 2f(y) for all x, y ∈ X. Furthermore, they proved the generalized Hyers-Ulam stability of the functional equation (1) in complex Banach spaces. In this paper, we wi...