We investigate products of sets reals with combinatorial covering properties. A topological space satisfies S 1 ( ? , ) if for each sequence point-cofinite open covers the space, one can pick element from cover and obtain a space. prove that, there is an unbounded tower, then nontrivial set satisfying in all finite powers. In contrast to earlier results, our proof does not require any additiona...

starting from two-dimensional (2d) equations of motion, discretized formulations for transient behavior of soil-structure interaction problems have been derived. two different dynamic infinite elements taking into account single and two-wave types are presented in transformed space. by coupling the infinite elements with standard finite elements, an ordinary finite element procedure is used for...