determines if this term is of the form `` f1 = f2 '' where f1 is the specified field and f2 is another field . if so , the method returns the name of that field . if not , the method returns null . concode_field_sep Expression lhs concode_elem_sep Expression rhs concode_field_sep Constant equatesWithConstant concode_elem_sep int reductionFactor concode_elem_sep boolean appliesTo concode_elem_sep boolean isSatisfied concode_elem_sep String toString