reserve
  S for (4,1) integer bool-correct non empty non void BoolSignature,
  X for non-empty ManySortedSet of the carrier of S,
  T for vf-free integer all_vars_including inheriting_operations free_in_itself
  (X,S)-terms VarMSAlgebra over S,
  C for (4,1) integer bool-correct non-empty image of T,
  G for basic GeneratorSystem over S,X,T,
  A for IfWhileAlgebra of the generators of G,
  I for integer SortSymbol of S,
  x,y,z,m for pure (Element of (the generators of G).I),
  b for pure (Element of (the generators of G).the bool-sort of S),
  t,t1,t2 for Element of T,I,
  P for Algorithm of A,
  s,s1,s2 for Element of C-States(the generators of G);
reserve
  f for ExecutionFunction of A, C-States(the generators of G),
  (\falseC)-States(the generators of G, b);
reserve u for ManySortedFunction of FreeGen T, the Sorts of C;

theorem Th21:
  for S being non empty non void ManySortedSign
  for o being OperSymbol of S st the_arity_of o = {}
  for A being MSAlgebra over S holds Args(o,A) = {{}}
  proof
    let S be non empty non void ManySortedSign;
    let o be OperSymbol of S;
    assume A1: the_arity_of o = {};
    let A be MSAlgebra over S;
    thus Args(o,A) = product ((the Sorts of A)*the_arity_of o) by PRALG_2:3
    .= {{}} by A1,CARD_3:10;
  end;
