SearcharxivSearch

arXiv subjects

Eugene Perchik

Publications and source records attributed to Eugene Perchik.

2 recordsLinked to original sources

Methodology of Syntheses of Knowledge: Overcoming Incorrectness of the Problems of Mathematical Modeling (revised version, March 2005)

J. Hadamard's ideas about the correct formulation of the problems of mathematical physics have been analyzed. In this connection various interpretations of the directly related Banach theorem about the inverse operator has been touched. The contemporary apparatus of mathematical modeling is shown to be in a drastic contradiction with concepts of J. Hadamard, S. Banach and a number of other outstanding scientists in the sense that the priority is given to the realization of algorithms, which actually imply that ill-posed problems are adequate to real phenomena. A new method is developed for solving problems traditionally associated with the Fredholm integral equation of the first kind that admits of their reduction to Fredholm integral equation of the second kind with properties most favorable for the numerical realization. It is demonstrated that a wide circle of problems can be reduced to two-dimensional Fredholm integral equations of the first kind; these are linear boundary-value and initial-boundary-value problems with variable coefficients, non-canonical domain of definition and others. The elaborated algorithm is shown to be directly applicable to them and may be used for testing their solvability. In discussing the formulation of problems of mathematical physics, considerable attention is paid to methodological aspects. Conclusions about cause-and-effect relations are argued to be essentially illegitimate when the solution of a problem reduces to a primitive renaming of known and unknown functions of a corresponding direct problem. The aim of this work is a constructive realization of J. Hadamard's opinion that physically meaningful problems are always well-posed.

math-ph

Methodology of Syntheses of Knowledge: Overcoming Incorrectness of the Problems of Mathematical Modeling

J. Hadamard's ideas of correct formulation of problems of mathematical physics as well as related Banach's theorem on the inverse operator are analyzed. Modern techniques of numerical simulations are shown to be in drastic contradiction to the concepts of J. Hadamard, S. Banach and a number of other outstanding scientists in the sense that the priority is given to the realization of inefficient algorithms, based on a belief that ill-posed problems are adequate to real phenomena. A new method of the solution of problems, traditionally associated with Fredholm integral equations of the first kind, is developed. Its key aspect is a constructive use of possibilities of the functional space $l_2$ to ensure the conditions of correctness. A well-known phenomenon of smoothing of information is taken into account by means of a special composition that explicitly involves the sought function and is infinitesimal in the space $L_2$. By relatively simple transformations, the outlined class of problems is reduced to the solution of Fredholm integral equations of the second kind with properties most favorable for the numerical realization. We demonstrate a reduction to Fredholm integral equations of the first kind and, correspondingly, a possibility to extend the suggested approach to wide classes of linear and nonlinear boundary-value and initial-boundary-value problems. We put forward arguments that the determination of causal relationships, based on the formulation restricted to a primitive renaming of known and unknown functions of the corresponding direct problem, is essentially illegitimate.

math-ph