Another proof to Kotschick-Morita's Theorem of Kontsevich homomorphism

Abstract

In \cite{KOT:MORITA}, Kotschick and Morita showed that the Gel'fand-Kalinin-Fuks class in $\ds \HGF{7}{2}{}{8}$ is decomposed as a product $\eta\wedge \omega $ of some leaf cohomology class $\eta$ and a transverse symplectic class $\omega$. In other words, the Kontsevich homomorphism $\ds\omega\wedge :\HGF{5}{2}{0}{10} \rightarrow\HGF{7}{2}{}{8}$ is isomorphic. In this paper, we give proof for the Kotschick and Morita's theorem by using the Gr\"obner Basis theory and computer symbol calculations.