On approximate solutions of a functional equation in the class of differentiable functions
On approximate solutions of a system of functional equations
On approximate solutions of functional equations of countable order.
On approximate solutions of the Pexider equation.
On approximate solutions of the Pexider equation. (Summary).
On Baire measurable solutions of some functional equations
We establish conditions under which Baire measurable solutions f of defined on a metrizable topological group are continuous at zero.
On Bimorphisms and Quadratic Forms on Groups
On Bimorphisms and Quadratic Forms on Groups. (Short Communications).
On bounded time-dependent perturbations of operator cosine functions.
On Cauchy differences of all orders.
On Cauchy-type functional equations.
On Characterizing x... .
On continuous composition operators
Let I ⊂ ℝ be an interval, Y be a normed linear space and Z be a Banach space. We investigate the Banach space Lip₂(I,Z) of all functions ψ: I → Z such that , where [r,s,t;ψ]:= ((s-r)ψ(t)+(t-s)ψ(r)-(t-r)ψ(s))/((t-r)(t-s)(s-r)). We show that ψ ∈ Lip₂(I,Z) if and only if ψ is differentiable and its derivative ψ’ is Lipschitzian. Suppose the composition operator N generated by h: I × Y → Z, (Nφ)(t):= h(t,φ(t)), maps the set (I,Y) of all affine functions φ: I → Y into Lip₂(I,Z). We prove that if N is...
On continuous solutions of a functional equation
This paper discusses continuous solutions of the functional equation φ[f(x)] = g(x,φ(x)) in topological spaces.
On convolution type functional equations.
On D'Alembert's functional equation on a Abelian group.
On derivations on certain function spaces and their relation to the differential operator. (Über Derivationen auf gewissen Funktionenräumen und deren Beziehung zum Differentiationsoperator.)
On Existance Of Expansion Of A Complex Function
On existence of expansion of a complex function.
On expanding iteration semigroups of set-valued functions.