Spinning fluids: A group theoretical approach

A Group - theoretical Approach to Gabor Analysis

Determination of Higher Order Optic Flow: A Group Theoretical Approach

We need higher order properties of the ow eld induced on the retina by an object moving in a 3D scene, in order to infer properties such as distance, tilt, slant, or curvature of the object. Direct di erentiation of a measured ow eld is not feasible in practice because not only the ow, but also the measurement errors are di erentiated. In this paper, we propose a group theoretical framework for...

On a group-theoretical approach to the curl operator

We utilize group-theoretical methods to develop a matrix representation of differential operators that act on tensors of any rank. In particular, we concentrate on the matrix formulation of the curl operator. A self-adjoint matrix of the curl operator is constructed and its action is extended to a complex plane. This scheme allows us to obtain properties, similar to those of the traditional cur...

Structures and phase transitions in perovskites--a group-theoretical approach.

Applications of computer-based group-theoretical methods to perovskite crystallography are reviewed. Such methods furnish a systematic account of the effects on the high-symmetry parent structure of diverse distortions. New results are presented for elpasolites (ordered double perovskites) when both ferroelectric cation displacement and simple octahedral tilting are allowed. Group-theoretical r...

A Group Theoretical Approach to Disjoint Paths in Directed Graphs

This is in general a hard problem The problem is NP complete Knuth cf even if we restrict ourselves to planar undirected graphs Lynch assuming that k is variable On the other hand it is a deep result of Robertson and Seymour that for each xed k the problem can be solved in polynomial time in any undirected graph However for directed graphs the problem remains di cult even for k This was shown b...