reserve G for non empty DTConstrStr,
  s for Symbol of G,
  n,m for String of G;
reserve n1,n2,n3 for String of G;

theorem Th3:
  s ==> n implies <*s*> ==> n
proof
  assume
A1: s ==> n;
  take n1 = <*>(the carrier of G), n2 = <*>(the carrier of G), n3 = n, s;
  thus <*s*> = n1^<*s*> by FINSEQ_1:34
    .= n1^<*s*>^n2 by FINSEQ_1:34;
  thus n = n1^n3 by FINSEQ_1:34
    .= n1^n3^n2 by FINSEQ_1:34;
  thus thesis by A1;
end;
