  The main result of this paper is the explicit computation of the equations
defining the moduli space of triples $(C,p,z)$ (where $C$ is an integral and
complete algebraic curve, $p$ a smooth rational point and $z$ a formal
trivialization around $p$) in the infinite Grassmannian of $k((t))$. This is
achieved by introducing infinite Grassmannians, tau and Baker-Ahkiezer
functions algebraically and by proving an Addition Formula for tau functions.
