How to find is any truck share same edge in same time?
Answered
Hello,
This is just a continuation of the question How to model all truck the same speed in a path?
ensure is any trucks share the same road segment will make platoon (at the same time, same edge, same segment)
the equation below
\[\begin{equation}
\sum_{e_{ij}\in E}^{k}{\ x_{i,j,t\ }^k==\ \sum_{e_{ij\ \in\ E}}^{w}{\ x_{i,j,t\ }^w\rightarrow\ \ \ q_{i,j}^{k,w}\ =1}}
\end{equation}\]
\(q_{i,j}^{k,w}\) Set a binary variable is true if tuck k and w on platoon on edge \(e_{ij}\)
My code has SyntaxError
set_time =[1000, 700, 802, 905, 770, 800, 850, 500]
tim_truck = {}
for k in trucks:
tim_truck[k] = mdl.addVars(location, set_time, vtype=GRB.BINARY, name="locate_"+str(k)+"_")
platoon = mdl.addVar(vtype= GRB.BINARY, name="platoon")
mdl.addConstrs( gp.quicksum( tim_truck[k][l[0],l[1],t] for t in set_time for k in trucks ) == gp.quicksum( tim_truck[w][l[0],l[1],t] for t in set_time for w in trucks ) if k != w for l in location >> platoon = 0)
Thank you
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Gurobi Staff
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Hi John,
You are trying to use an indicator constraint. However, indicator constraints are used to state that
\[b=1 \rightarrow a^T x \leq b\]
meaning that if a binary variable \(b\) equals 1 then the linear constraint \(a^T x \leq b\) should hold, see the documentation of indicator constraints. In your case, the first statement reads \(y = z\) with \(y=\sum x_{i,j,t}^k, z=\sum_{i,j,t}^w}) which does not fit the indicator constraint syntax.
What you are looking for is described in the stackoverflow post Converting conditional constraints to linear constraints in Linear Programming.
Best regards,
Jaromił0 -
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