Conjugacy of P-configurations and nonlinear solutions to a certain conditional Cauchy equation.
Fixed points, inner product spaces, and functional equations.
Generalized Hyers-Ulam-Rassias theorem in Menger probabilistic normed spaces.
Generalized orthogonal stability of some functional equations.
Linear functional inequalities-a general theory and new special cases [Book]
Local stability of the additive functional equation and its applications.
On some approximate functional relations stemming from orthogonality preserving property.
On the Stability of Orthogonal Additivity
We deal with the stability of the orthogonal additivity equation, presenting a new approach to the proof of a 1995 result of R, Ger and the second author. We sharpen the estimate obtained there. Moreover, we work in more general settings, providing an axiomatic framework which covers much more cases than considered before by other authors.
Orthogonality preserving property, Wigner equation, and stability.
Orthogonally additive mappings on Hilbert modules
We study the representation of orthogonally additive mappings acting on Hilbert C*-modules and Hilbert H*-modules. One of our main results shows that every continuous orthogonally additive mapping f from a Hilbert module W over 𝓚(𝓗) or 𝓗𝓢(𝓗) to a complex normed space is of the form f(x) = T(x) + Φ(⟨x,x⟩) for all x ∈ W, where T is a continuous additive mapping, and Φ is a continuous linear mapping.
Rank of matrices and the Pexider equation.
Stability of a generalized Euler-Lagrange type additive mapping and homomorphisms in -algebras.