Soit C(•,0):S 1 →R 2 une courbe lisse plongee dans le plan. Alors C:S 1 ×[0,T)→R 2 existe en satisfaisant δC/δt=K•N, ou K est la courbure de C, et N est son vecteur unite normal entrant. C(•,t) est… Expand

is called the harmonic map heat flow. In their paper [3], Eells and Sampson introduced this flow and proved that if the target N has non-positive sectional curvature, then the solution exists for all… Expand

We show that no cocompact discrete group based on solvgeometry, Sol, is almost convex. This reflects the geometry of Sol, and implies that the Cayley graph of a cocompact discrete group based on Sol… Expand

If a Lie algebra g can be generated by M of its elements E1, . . . , EM , and if any other Lie algebra generated by M other elements F1, . . . , FM is a homomorphic image of g under the map Ei → Fi,… Expand

This paper investigates the suitability of various techniques of visualizing the set of possible orientations of a rigid three-dimensional object in a topological space with three degrees of freedom.Expand