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On some iteration semigroups

Janusz Brzdęk (1995)

Archivum Mathematicum

Let F be a disjoint iteration semigroup of C n diffeomorphisms mapping a real open interval I onto I . It is proved that if F has a dense orbit possesing a subset of the second category with the Baire property, then F = { f t f t ( x ) = f - 1 ( f ( x ) + t ) for every x I , t R } for some C n diffeomorphism f of I onto the set of all reals R . The paper generalizes some results of J.A.Baker and G.Blanton [3].

On the convergence of sequences of iterates of random-valued vector functions

Rafał Kapica (2007)

Annales Polonici Mathematici

Given a probability space (Ω,,P) and a subset X of a normed space we consider functions f:X × Ω → X and investigate the speed of convergence of the sequence (fⁿ(x,·)) of the iterates f : X × Ω X defined by f¹(x,ω ) = f(x,ω₁), f n + 1 ( x , ω ) = f ( f ( x , ω ) , ω n + 1 ) .

On the formal first cocycle equation for iteration groups of type II

Harald Fripertinger, Ludwig Reich (2012)

ESAIM: Proceedings

Let x be an indeterminate over ℂ. We investigate solutions α ( s , x ) = n 0 α n ( s ) x n , αn : ℂ → ℂ, n ≥ 0, of the first cocycle equation α ( s + t , x ) = α ( s , x ) α t , F ( s , x ) , s , t , ( Co 1 ) in ℂ [[x]], the ring of formal power series over ℂ, where (F(s,x))s ∈ ℂ is an iteration group of type II, i.e. it is a solution of the translation equation F ( s + t , x ) = F ( s , F ( t , x ) ) , s , t , ( T ) of the form F(s,x) ≡ x + ck(s)xk mod xk+1, where k ≥ 2 and ck ≠ 0 is necessarily an additive function. It is easy to prove that the coefficient functions αn(s) of α ( s , x ) = 1 + n 1 α n ( s ) x n are polynomials in ck(s).It is possible to replace...

On the uniqueness of continuous solutions of functional equations

Bolesław Gaweł (1995)

Annales Polonici Mathematici

We consider the problem of the vanishing of non-negative continuous solutions ψ of the functional inequalities (1)   ψ(f(x)) ≤ β(x,ψ(x)) and (2)   α(x,ψ(x)) ≤ ψ(f(x)) ≤ β(x,ψ(x)), where x varies in a fixed real interval I. As a consequence we obtain some results on the uniqueness of continuous solutions φ :I → Y of the equation (3)  φ(f(x)) = g(x,φ(x)), where Y denotes an arbitrary metric space.

On zeros of differences of meromorphic functions

Yong Liu, HongXun Yi (2011)

Annales Polonici Mathematici

Let f be a transcendental meromorphic function and g ( z ) = f ( z + c ) + + f ( z + c k ) - k f ( z ) and g k ( z ) = f ( z + c ) f ( z + c k ) - f k ( z ) . A number of results are obtained concerning the exponents of convergence of the zeros of g(z), g k ( z ) , g(z)/f(z), and g k ( z ) / f k ( z ) .

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