Degeneration of the Hilbert pairing in formal groups over local fields

Abstract

For an arbitrary local field K (a finite extension of the field Q_p) and an arbitrary formal group law F over K, we consider an analog c_F of the classical Hilbert pairing. A theorem by S.V. Vostokov and I.B. Fesenko says that if the pairing c_F has a certain fundamental symbol property for all Lubin–Tate formal groups, then c_F = 0. We generalize the theorem of Vostokov–Fesenko to a wider class of formal groups. Our first result concerns formal groups that are defined over the ring O_K of integers of K and have a fixed ring O₀ of endomorphisms, where O₀ is a subring of O_K. We prove that if the symbol c_F has the above-mentioned symbol property, then c_F = 0. Our second result strengthens the first one in the case of Honda formal groups. The paper consists of three sections. After a short introduction in Section 1, we recall basic definitions and facts concerning formal group laws in Section 2. In Section 3, we state and prove two main results of the paper (Theorems 1 and 2). Refs. 8.