toplevel "A";
"A" pand "B" "BE4";
"B" pand "C" "BE3";
"C" pand "BE1" "BE2";
"BE1" lambda=0.5 dorm=3;
"BE2" lambda=0.5 dorm=3;
"BE3" lambda=0.5 dorm=3;
"BE4" lambda=0.5 dorm=3;