Associative Formal Power Series in Two Indeterminates Publications, to be read On the formal second cocycle equation for iteration groups of type II On 1-dimensional formal group laws in characteristic zero

On 1-dimensional formal group laws in characteristic zero

Jointly written with JENS SCHWAIGER Aequationes Mathematicae pages 1-6, 2014.

Abstract: Let 𝕂 be a field of characteristic zero or, more general, a Q-algebra. A formal power series F(x,y)=x+y+i,j≥ 1 ai,jxiyj𝕂[[x,y]] is called a 1-dimensional formal group law if F(F(x,y),z)=F(x,F(y,z)). Using some elementary methods, we prove that for every 1-dimensional formal group law F(x,y) there exists a formal power series f(x)=x+n≥ 2fnx n𝕂[[x]] so that F(x,y)=f-1(f(x)+f(y)).


harald.fripertinger "at" uni-graz.at, October 12, 2017

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