Публикации

Global bifurcations in the generic one-parameter families that unfold a vector field with a separatrix loop on the two-sphere are described. The sequence of bifurcation that occurs is in a sense in ono-to-one correspondence with finite sets on a circle having some additional structure on them. Families under study appear to be structurally stable. The main tool is the Leontovich-Mayer-Fedorov (LMF) graph, analog of the separatrix sceleton - an invariant of the orbital topological classification of the vector fields on the two-sphere. Its properties and applications are described. 

We propose an r-variable version of Kostka-Shoji polynomials K_{λμ} for r-multipartitions λ, μ. Our version has positive integral coefficients and encodes the graded multiplicities in the space of global sections of a line bundle over Lusztig’s iterated convolution diagram for the cyclic quiver Ã_{r−1}.