Some base axioms for topology involving enumerability
The author obtains the classification of all invariant Einstein metrics on the following homogeneous spaces: , , , . Combining this with the results of other authors, the classification of all invariant Einstein metrics on all compact simply connected homogeneous spaces admitting a homogeneous Riemannian metric of positive sectional curvature is obtained.
Given a fibered manifold , a 2-connection on means a section . The authors determine all first order natural operators transforming a 2-connection on and a classical linear connection on into a connection on . (The proof implies that there is no first order natural operator transforming 2-connections on into connections on .) Using this result, the authors deduce several properties of characterizable connections on .
We describe a parallel implementation of the Balancing Domain Decomposition by Constraints (BDDC) method enhanced by an adaptive construction of coarse problem. The method is designed for numerically difficult problems, where standard choice of continuity of arithmetic averages across faces and edges of subdomains fails to maintain the low condition number of the preconditioned system. Problems of elasticity analysis of bodies consisting of different materials with rapidly changing stiffness may...