theorem
 dom(p^<%e%>) = dom p \/ {card p}
proof
 thus dom(p^<%e%>) = dom(p +* Shift(<%e%>, card p)) by Th74
      .= dom p \/ dom Shift(<%e%>,card p) by FUNCT_4:def 1
      .= dom p \/ {card p} by Th84;
 end;
