  Systems with constraints pose problems when they are quantized. Moreover, the
Dirac procedure of quantization prior to reduction is preferred. The projection
operator method of quantization, which can be most conveniently described by
coherent state path integrals, enables one to directly impose a regularized
form of the quantum constraints. This procedure also overcomes conventional
difficulties with normalization and second class constraints that invalidate
conventional Dirac quantization procedures.
