Simplest Singular Points of 1-forms Invariant with Respect to an Action of Group of Order Three / F. I. Mamedova. // Vestnik Moskovskogo Universiteta. Seriya 1. Matematika. Mekhanika. 2018. № 5. P. 60-63 [Moscow Univ. Math. Bulletin. Vol. 72, N 2, 2017. P. 199-202].

Singular points that cannot be removed by small deformations of 1-forms and invariant with respect to the action of a cyclic group of order 3 are classified. It is proved that for {\mathbb Z}_3-invariant 1-forms the equivariant index of a singular point, as an element of the representation ring of the group, coincides with the class of the representation on the space of germs of forms of highest order factored by the subspace of forms divisible by the given 1-form.

Key words: 1-forms, group actions, equivariant deformations.