Originally posted by: ShaCplex

Hi,

for a given trip t and a given aircraft a, if assign[t][a] is 0 then you do not want to propagate anything but that is what you do here.

Let me call M a number that is greater than the number of trips times the number of aircrafts.

Can you change

forall(t in trips, a in aircrafts) sum(k in trips: k.arrTime>=t.DepTime && k.DepTime<=t.arrTime && k.tripID!=t.tripID) 
(assign[k][a] )+ assign[t][a]<= 1;

into

forall(t in trips, a in aircrafts) sum(k in trips: k.arrTime>=t.DepTime && k.DepTime<=t.arrTime && k.tripID!=t.tripID) 
(assign[k][a] ) <= (1-assign[t][a])*M;

regards

Originally posted by: ShaCplex

Hi Alex,

Thank u very much! many days of my effort has paid off !!

I am really thankful and really appreciate your help.