programming / logic ?

[traders10@xxxx]

Lets say I have a set up event su = cross(x, y); 

Then I look for a trigger event, z, over the next 4 days. Z is some 
arbitrary complex function.

Does this logic work if the trigger occurs, for example, 3 days after 
the set up event? 

buy = su and ( ref(z,1) or ref(z,2) or ref(z,3) or ref(z,4));



If this is wrong, what approach should I be using for this situation?
TIA
Trader