the initial-boundary value formulation for the einstein equations has a number of special features when compared with that for other partial differential equations. these issues are briefly discussed, and an approach to prove local in time existence is presented. the main idea is to rewrite einstein\'s equations into an equivalent form, called weyl system. this work follows the main idea in, though is simpler than, the work by friedrich and nagy, comm. math. phys. 201, 619, (1999).