toplevel "A";
"A" and "T1" "T2";
"T1" pand "B1" "B2"; 
"T2" pand "B3" "B4";
"X" seq "B4" "B3";
"B1" lambda=0.7 dorm=0.3;
"B2" lambda=0.5 dorm=0.3;
"B3" lambda=0.5 dorm=0.3;
"B4" lambda=0.7 dorm=0.3;