Small divisor problems via a general theorem

Compensations in small divisor problems

Several small divisor problems arising in the perturbative theory of Hamiltonian and La-grangian systems are considered. A general method that allows to prove compensations among the elementary contributions of the formal power series expansions associated to invariant surfaces is presented.

Accurate Strategies for Small Divisor Problems

Many interesting problems in mechanics are close to systems that can be solved exactly. In such systems it is natural to consider perturbative expansions about the known system. Frequently it is possible to compute all of the terms in the expansion recursively, which can lead to expressions involving denominators that become arbitrarily small. The convergence of these expansions is difficult to...

A More General Version of the Costa Theorem

In accordance with the Costa theorem, the interference which is independent of the channel input and known non-causally at the transmitter, does not affect the capacity of the Gaussian channel. In some applications, the known interference depends on the input and hence has some information. In this paper, we study the channel with input dependent interference and prove a capacity theorem that n...

A strong convergence theorem for solutions of zero point problems and fixed point problems

Zero point problems of the sum of two monotone mappings and fixed point problems of a strictly pseudocontractive mapping are investigated‎. ‎A strong convergence theorem for the common solutions of the problems is established in the framework of Hilbert spaces‎.

A General Correlation Theorem