for S being non void Signature
for X, Y being ManySortedSet of the carrier of S st X c= Y & X is with_missing_variables holds
( Terminals (DTConMSA X) c= Terminals (DTConMSA Y) & the Rules of (DTConMSA X) c= the Rules of (DTConMSA Y) & TS (DTConMSA X) c= TS (DTConMSA Y) )