A type of Link used in OpenCog to define extensional implication.
For more information, see this page
ExtensionalImplicationLink <TV> P Q
is equivalent to
Thus the TV strength is calculated as follows
TV.s = Sum_X f(P(X), Q(X)) / Sum_X P(X)
assuming all x are uniformly distributed, else
TV.s = Sum_X f(P(X), Q(X)) * X.s / Sum_X P(X) * X.s
if we want to consider a non uniform mass function. f as currently implemented is the min function.