\model{

\constant{LAMBDA}{1.0}
\constant{MU}{6.0}

\statevector{
  \type{int}{p1, p2, p3, p4}
}

\initial{
  p1 = 1;
  p2 = 0;
  p3 = 0;
  p4 = 0;
}

\transition{t1}{
  \condition{p1 > 0}
  \action{
    next->p1 = p1 - 1; 
    next->p2 = p2 + 1;
  }  
  \rate{ LAMBDA }
}

\transition{t2}{
  \condition{p2 > 0}
  \action{
    next->p2 = p2 - 1;
    next->p3 = p3 + 1;
  }
  \rate{ LAMBDA }
}

\transition{t3}{
  \condition{p3 > 0}
  \action{
    next->p3 = p3 - 1; 
    next->p1 = p1 + 1;
  }  
  \rate{ LAMBDA }
}

\transition{t4}{
  \condition{p2 > 0}
  \action{
    next->p2 = p2 - 1;
    next->p4 = p4 + 1;
  }
  \rate{ MU }
}

\transition{t5}{
  \condition{p4 > 0}
  \action{
    next->p4 = p4 - 1; 
    next->p1 = p1 + 1;
  }  
  \rate{ MU }
}

}

\solution{
  \method{gauss}
}

\performance{
        \statemeasure{1 token in place p_1 and 1 token in place p3}{
                \estimator{mean}
                \expression{ p1==1 && p3 == 1}
	}
}