The author considers the Klein-Gordon equation for -dimensional flat spacetime. He is interested in those coordinate systems for which the equation is separable. These coordinate systems are explicitly known and generally do not cover the whole plane. The author constructs tensor fields which he can use to express the locus of points where the coordinates break down.
The author studies the holonomy group of a simply connected indecomposable and reducible Lorentzian spin manifold under the condition that they admit parallel spinors. He shows that there are only two possible situations: either the manifold is a so-called Brinkmann wave or it has Abelian holonomy and is a pp-manifold – a generalization of a plane-wave. The author gives also sufficient conditions for a Brinkmann wave to have as holonomy the semidirect product of holonomy group of a Riemannian manifold...
Earlier work has examined the frequency of symbol and expression use in mathematical documents for various purposes including mathematical handwriting recognition and forming the most natural output from computer algebra systems. This work has found, unsurprisingly, that the particulars of symbol and expression vary from area to area and, in particular, between different top-level subjects of the 2000 Mathematical Subject Classification. If the area of mathematics is known in advance, then an area-specific...
We present a summary of our work in progress related to mathematical formulae recognition. Our approach is based on the structural construction paradigm and two-dimensional grammars. It is a general framework and can be successfully used in the analysis of images containing objects exhibiting rich structural relations. In contrast to most of all other known approaches, the method does not treat symbols segmentation and structural analysis as two separate processes. This allows the system to solve...