Equations of the moduli of pointed curves in the infinite Grassmannian

The main result of this paper is the explicit computation of the equations defining the moduli space of triples (C,p,phi), where C is an integral and complete algebraic curve, p a smooth rational point and phi a certain isomorphism. This is achieved by introducing algebraically infinite Grassmannians, tau and Baker-Ahkiezer functions and by proving an Addition Formula for tan functions.