Description: Define the Godel-set of universal quantification. Here N e.om
corresponds to vN , and U represents another formula, and this
expression is [ A. x ph ] = A.g N U where x is the N -th
variable, U = [ ph ] is the code for ph . Note that this is a
class expression, not a wff. (Contributed by Mario Carneiro, 14-Jul-2013)