ensemble non borné

OBS: Tiré du résumé de l'article de A. Villani, Processi di controllo con parametri distribuiti in insiemi non limitati : controllabilita completa esatta, publié dans les ""Annali di matematica pura e applicata"", 1983, vo. 83, no. 4, p. 19-33.

CONT: One says that the unbounded set S is self similar with respect to the ratio r and the focus F in S when the set r(S) is identical to S except possibly for a displacement.