We give an explicit form for the Lorentzian vertices recently introduced for
possibly defining the dynamics of loop quantum gravity. As a result of so
doing, a natural regularization of the vertices is suggested. The regularized
vertices are then proven to be finite. An interpretation of the regularization
in terms of a gauge-fixing is also given.Comment: 16 pages; Added an appendix presenting the gauge-fixing
interpretation, added three references, and made some minor change