Let X be a reflexive Banach space and (Ω,,μ) be a probability measure space. Let T: M(μ;X) → M(μ;X) be a linear operator, where M(μ;X) is the space of all X-valued strongly measurable functions on (Ω,,μ). We assume that T is continuous in the sense that if (fₙ) is a sequence in M(μ;X) and $li{m}_{n\to \infty }fₙ=f$ in measure for some f ∈ M(μ;X), then also $li{m}_{n\to \infty }Tfₙ=Tf$ in measure. Then we consider the functional equation f = (T-I)h, where f ∈ M(μ;X) is given. We obtain several conditions for the existence of h ∈ M(μ;X) satisfying...

We study the generalized Dhombres functional equation f(zf(z)) = ϕ(f(z)) in the complex domain. The function ϕ is given and we are looking for solutions f with f(0) = w0 and w0 is a primitive root of unity of order l ≥ 2. All formal solutions for this case are described in this work, for the situation where ϕ can be transformed into a function which is linearizable and local analytic in a neighbourhood of zero we also show...

We study k th order systems of two rational difference equations $$x_n=\frac{\alpha +{\sum }_{i=1}^k{\beta }_i{x}_{n-1}+{\sum }_{i=1}^k{\gamma }_i{y}_{n-1}}{A+{\sum }_{j=1}^k{B}_j{x}_{n-j}+{\sum }_{j=1}^k{C}_j{y}_{n-j}},y_n=\frac{p+{\sum }_{i=1}^k{\delta }_i{x}_{n-i}+{\sum }_{i=1}^k{\epsilon }_i{y}_{n-i}}{q+{\sum }_{j=1}^k{D}_j{x}_{n-j}+{\sum }_{j=1}^k{E}_j{y}_{n-j}}n\in \mathbb{N}$$ . In particular, we assume non-negative parameters and non-negative initial conditions, such that the denominators are nonzero. We develop several approaches which allow us to extend well known boundedness results on the k th order rational difference equation to the setting of systems in certain cases.

In this paper some types of complex vector systems of partial linear and non-linear functional equations are solved.