changeAttributes(ident uid, ident id, ident sheetId, double maxPoints) {
  assume exists /account[uid]/assistant[id];
 
  assume exists /exercise[id]/sheet[sheetId]; # implies the existence of the exercise
 
  assume maxPoints >= 0;
  assume /exercise[id]/student[x]/result[sheetId]/points <= maxPoints;
 
  update /exercise[id]/sheet[sheetId]/maxPoints maxPoints;
}