When uploading my model, I receive an error corresponding to every constraint that I express. The error seems to be related with the work “subject”, part of the “subject to” with which I introduce the constraint. The same happens if I write “s.t.” instead of “Subject to”.

The error I get is the following:

modello.mod, line 18 (offset 699):

syntax error

context: >>> subject <<< to capacity_pads {p in P, t in T} : sum{k in K} x_land[p, t, k] + sum{k in K} x_to[p,t,k] <= Cp[p];

My model is the following:

set P; # insieme di pads

set T; # istanti di tempo

set K; # aerei

param Cp{p in P}; # capacità pads

param T_land; # tempo landing

param T_to; # tempo takeoff

param T_ta; # tempo turnaround

param n_stand; # numero stands

param t_segnato in T;

var x_land {p in P, t in T, k in K} binary; # >= 0; # aereo k che atterra su pad P al tempo T

var x_to {p in P, t in T, k in K} binary;# >= 0; # aereo k che decolla da pad P al tempo T

maximize capacity : sum {p in P, t in T, k in K} x_land[p, t, k] + sum {p in P, t in T, k in K} x_to [p, t, k]

subject to capacity_pads {p in P, t in T} : sum{k in K} x_land[p, t, k] + sum{k in K} x_to[p,t,k] <= Cp[p];

subject to pad_decolli {t in T, k in K}: x_land[1,t,k] = 0;

subject to pad_atterraggi {t in T, k in K}: x_to [2,t,k] = 0;

(there are other constraints but they are not relevant for this problem)

Any help would be really appreciated.