Logarithms of formal groups over Hopf algebras

Abstract

The aim of this paper is to prove the following result. For any commutative formal group $\mathfrak{F}(x\otimes 1,1\otimes x),$ which is considered as a formal group over $H_{\mathbb{Q}},$ there exists a homomorphism to a formal group of the form $\mathfrak{c}+x\otimes 1+1\otimes x,$ where $\mathfrak{c}\in H_{\mathbb{Q}}\underset{R_{\mathbb{Q}}}{\hat{\otimes }}{H}_{\mathbb{Q}}$ such that $(\id \otimes ε){\frak c}=0= (ε\otimes \id){\frak c}.$

5 pages