In this paper, by 1-sequence-covering mappings, the relations between metric spaces and spaces with (σ-) locally countable weak bases are established. These are answers to Alexandroff's some problems.
With the rapid development of computing power and information processing ability, some efficient numerical methods are developed to deal with the complex problems. In this paper, efficient finite difference method is introduced to solve the nonlinear Laplacian problem, in which two variables can be approximated simultaneously. Calculation scheme is… (More)
In this paper, we program a procedure using Maple's packages, with it we can realize mechanical proving of some theorems in elementary geometry.