Vladislav Kirilovich Dzyadyk - Ukrainian mathematician. Main fields: approximation theory, theory of differential and integral equations, computational mathematics. For more information try one of the following Dzjadyk, Dzaidyk, Dzyadyk in a Web search engine.
a-method - approximation method for linear differential equations with polynomial coefficients. The method gives asymptotically best approximation in Chebyshev metric. It can be also applied for lde's with non polynomial coefficients and for partial differential equations.
Main monograph: "Approximation methods for solutions of differential and integral equations", V. K. Dzyadyk, Naukova Dumka, Kiev, 1988. http://www.amazon.com/gp/product/9067641944/ref=nosim/002-9477136-5245608?n=283155