Formal inverse
= Formal inverse
{title2=$i_F(X)$}
Every one-dimensional <formal group law> has a unique formal inverse $i_F(X)=-X+O(X^2)$ satisfying $F(X,i_F(X))=0$. Comparing coefficients recursively determines it degree by degree.
= Formal inverse
{title2=$i_F(X)$}
Every one-dimensional <formal group law> has a unique formal inverse $i_F(X)=-X+O(X^2)$ satisfying $F(X,i_F(X))=0$. Comparing coefficients recursively determines it degree by degree.