A Banach algebraic Approach to the Borsuk-Ulam Theorem

Using methods from the theory of commutative graded Banach algebras, we obtain a generalization of the two dimensional Borsuk-Ulam theorem as follows: Let $\varphi :S^2\to S^2$ be a homeomorphism of order n and $\lambda \mathrm{\ne }1$ be an nth root of the unity, then for every complex valued continuous function $f$ on $S^2$ the function $\sum_{i=0}^{n-1} \lambda^{i}f(\phi^{i}(x))$mustbevanishedatsomepointof$S^{2}$. We give a generalization in term of action of compact groups. We also discuss about some noncommutative versions of the Borsuk- Ulam theorem