Determine the function to be used in the conjunctive aggregation step of evaluate().
and_function(method = EnumEvalMethod, and = NULL)Returns the function and if not NULL.
Otherwise, it determines the result depending on method:
Fails with an error if the result is not an R function.
One of: "set" (default), "prob", "fuzzy" or "fuzzynorm".
Some conjunctive aggregation function of the form function(num_vector), or NULL.
evaluate, or_function().