I keep running into an error with AMPL wherein whenever I try to model my mod file I get an error: d is not defined [closed]

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I keep running into an error with AMPL wherein whenever I try to model my mod file I get an error:

giap.mod, line 23 (offset 1996):  d is not defined
context:  {(d, b)  >>> :  <<< d in Donors_Deliver, b in All_FoodBank}

# Donor ke Gudang Makanan

# Sets
set Time;                          # Time periods in the planning horizon
set Donors_Deliver;                # Donors that deliver food items to food banks
set Collection_Donors;             # Donors that require collection of food items by food banks
set Financial_Donors;              # Donors that provide financial donations to food banks
set All_Donors := Donors_Deliver union Collection_Donors union Financial_Donors;  # All donors, D = DD union CD union FD (subsets are pairwise disjoint)
set Existing_FoodBank;             # Existing food bank warehouses at the beginning of the planning horizon
set Potential_Sites;               # Potential sites for locating new food bank warehouses
set All_FoodBank := Existing_FoodBank union Potential_Sites;  # All food bank locations, B = OB union PB and OB intersect PB = empty set
set Received_FoodBank within (Donors_Deliver cross All_FoodBank);  # Food banks that can receive food products from donor d in DD, Bd ⊆ B
set Served_Charities;              # Beneficiary organizations served by some food bank at the beginning of the planning horizon
set Hold_Charities;                # Non-profit organizations on hold, i.e., organizations on the waiting list of the food bank association
set All_Organisations := Served_Charities union Hold_Charities;  # All organizations, C = SC union HC and SC intersect HC = empty set
set FoodGroup;                     # Families of food products 
set Individual_Food {k in FoodGroup};  # Individual food items belonging to family k in K
set All_Product := union {k in FoodGroup} Individual_Food[k];  # All food products, P = union of Pk
set Levels;                        # Discrete capacity levels for storage areas/transport resources
set I;                             # Set asal (origin)
set J;                             # Set tujuan (destination)

# Define set All_destination as the union of all relevant relationships
set All_destination :=
    {(d, b) : d in Donors_Deliver, b in All_FoodBank}    # Donor ke Gudang Makanan
    union {(d, b) : d in Collection_Donors union Financial_Donors, b in All_FoodBank}    # Donor Pengumpulan/Sumbangan ke Gudang Makanan
    union {(b, c) : b in All_FoodBank, c in Served_Charities};

marcos · Accepted Answer · 2024-08-01 17:25:08Z

2

In your set expression {(d, b) : d in Donors_Deliver, b in All_FoodBank}, (d,b) needs to be a in some set, something like (d,b) in some_set, before you specify the filter conditions. There are many ways to express a set. For example,

{d in Donors_Deliver, b in All_FoodBank}

Moreover, your expression could be simplified into Donors_Deliver union All_FoodBank directly.

Another option could be using the "setof" operator, could be useful when generating more complex sets.

setof {d in Donors_Deliver, b in All_FoodBank: d <= 3 and d !=b} (d,2*b);

edited Aug 1, 2024 at 17:25

answered Aug 1, 2024 at 17:17

marcos

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