Let F be a C ∞ vector field defined near the origin O ∈ R , F (O) = 0, and (F ) be its local flow. Denote bŷ (F ) the set of germs of orbit preserving diffeomorphisms : R → R at O, and letˆ id (F ) , ( ≥ 0), be the identity component ofˆ (F ) with respect to the weak Whitney W topology. Thenˆ id (F ) ∞ contains a subset S (F ) consisting of maps of the form F α( ) ( ), where α : R → R runs over the space of all smooth germs at O.
It was proved earlier by the author that if F is a linear vector field, thenŜ (F ) =ˆ id (F ) 0In this paper we present a class of examples of vector fields with degenerate singularities at O for whichŜ (F ) formally coincides withˆ id (F ) 1 , i.e. on the level of ∞-jets at O. We also establish parameter rigidity of linear vector fields and "reduced" Hamiltonian vector fields of real homogeneous polynomials in two variables.
MSC:37C10