On Permanent vector-varieties in n-dimensions
http://dugi.udg.edu/item/http:@@@@hdl.handle.net@@10256.2@@8236
J. L. SYNGS [1951] has recently given a generalization to the Euclidean space of n dimensions of ZORAWSKI’S condition for the permanence of vector-lines in a moving fluid. The purpose of this note is to consider the more general case in which instead of vector-lines we have varieties of dimension r >= 1 defined by certain vector fields. We obtain a necessary and sufficient condition for the permanence of these r-dimensional vector-varieties in a moving fluid. The method we follow is analogous to that of SYNGE
Sociedade Portuguesa de Matematica
