/** Evaluate 'termName' membershipfunction at 'value' */
public double getMembership(String termName) {
MembershipFunction mf = getMembershipFunction(termName);
if( mf == null ) throw new RuntimeException("No such termName: \"" + termName + "\"");
return mf.membership(this.value);
}
/** Get 'termName' membershipfunction */
public MembershipFunction getMembershipFunction(String termName) {
LinguisticTerm lt = (LinguisticTerm) linguisticTerms.get(termName);