E + P -> E_P_1
E_P_1 -> E + P
E_P_1 -> E + M
M -> M1
E + M1 -> E_M1
E_M1 -> E + M1
E + M -> E_M
E_M -> E + M
E_M1 -> E + T
E_M -> E + T
E + P -> E_P_2
E_P_2 -> E + P
E_P_2 -> E + P2
P2 -> P21
E + P21 -> E_P21
E_P21 -> E + P21
E + P2 -> E_P2
E_P2 -> E + P2
E_P21 -> E + T
E_P2 -> E + T
E_P_1 -> T
E_P_2 -> T