We present a new method for the quantization of totally constrained systems
including general relativity. The method consists in constructing discretized
theories that have a well defined and controlled continuum limit. The discrete
theories are constraint-free and can be readily quantized. This provides a
framework where one can introduce a relational notion of time and that
nevertheless approximates in a well defined fashion the theory of interest. The
method is equivalent to the group averaging procedure for many systems where
the latter makes sense and provides a generalization otherwise. In the
continuum limit it can be shown to contain, under certain assumptions, the
``master constraint'' of the ``Phoenix project''. It also provides a
correspondence principle with the classical theory that does not require to
consider the semiclassical limit.Comment: 4 pages, Revte