A note on hamiltonian Lie group actions and Massey products

In this note we show that the property of having only vanishing triple Massey products in the equivariant cohomology is inherited by the set of fixed points of hamiltonian circle actions on closed symplectic manifolds. This result can be considered in a more general context of characterizing homotopic properties of Lie group actions. In particular, it can be viewed as a partial answer to the Allday-Puppe question about finding conditions ensuring the "formality" of G-actions.