reserve i for Nat,
  j for Element of NAT,
  X,Y,x,y,z for set;
reserve C for initialized ConstructorSignature,
  s for SortSymbol of C,
  o for OperSymbol of C,
  c for constructor OperSymbol of C;
reserve a,b for expression of C, an_Adj C;
reserve t, t1,t2 for expression of C, a_Type C;
reserve p for FinSequence of QuasiTerms C;
reserve e for expression of C;
reserve a,a9 for expression of C, an_Adj C;
reserve q for pure expression of C, a_Type C,
  A for finite Subset of QuasiAdjs C;
reserve T for quasi-type of C;

theorem
  for G being non empty DTConstrStr for s being Element of G
  for p being FinSequence st s ==> p
  holds p is FinSequence of the carrier of G
proof
  let G be non empty DTConstrStr;
  let s be Element of G;
  let p be FinSequence;
  assume s ==> p;
  then [s,p] in the Rules of G;
  then p in (the carrier of G)* by ZFMISC_1:87;
  hence thesis by FINSEQ_1:def 11;
end;
