The method of self-similar factor approximants is applied to calculating the critical exponents of the O(N)-symmetric ϕ<Superscript>4</Superscript> theory and of the Ising glass. It is demonstrated that this method, being much simpler than other known techniques of series summation in calculating the critical exponents,...</superscript>

Perturbation theory can be reformulated as dynamical theory. Then a sequence of perturbative approximations is bijective to a trajectory of dynamical system with discrete time, called the approximation cascade. Here we concentrate our attention on the stability conditions permitting to control...