upperCalculate lower bounds for a vector of sets with respect to the evidence structure. For more detail see upper
signature(x = "credal", sets = "character")obtain upper bounds for a vector of sets
signature(x = "credal", sets = "missing")obtain upper bounds for all singletons
signature(x = "mass", sets = "character")obtain the plausability, or upper bounds, for a vector of sets
signature(x = "mass", sets = "missing")obtain the plausability, or upper bounds, for all singletons