theorem Th40:
  \2(T,I) value_at (C,s) = 2
  proof
A1: \1(T,I) value_at(C,s) = 1 by Th37;
    thus \2(T,I) value_at(C,s)
    = (\1(T,I) value_at(C,s))+(\1(T,I) value_at(C,s)) by Th39
    .= 2 by A1,AOFA_A00:55;
  end;
