We present a rigorous regularization of Rovellis's generalized projection
operator in canonical 2+1 gravity. This work establishes a clear-cut connection
between loop quantum gravity and the spin foam approach in this simplified
setting. The point of view adopted here provides a new perspective to tackle
the problem of dynamics in the physically relevant
3+1 case.Comment: To appear in the procedings of the Third International Symposium on
Quantum Theory and Symmetries (QTS3), September 200