Business Objects & Instantiation

Visualization

The image below visualizes the data created below. For this example we have 5 different subsets with different elements.

Element (Business Object)

Each Element holds its name and value. All elements are contained in Sets.
Element.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace SetProblems
{
    /// <summary>
    /// creates an element for the Set Problem(s)
    /// </summary>
    public class Element : IElement
    {

        public Element(string name, double value)
        {
            this.Name = name;
            this.Value = value;
        }

        /// <summary>
        /// the value of the element
        /// </summary>
        public double Value { get; }

        public string Name { get; }

        public override string ToString() => this.Name;
    }
}

Set of Elements (Business Object)

Each Set holds different Elements and has a designated cost. Elements are stored in a way that the Model can ask if the Element is contained in this Set efficiently. There is also information about the Set being the original full Set or not.
Set_E.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace SetProblems
{
    /// <summary>
    /// creates a Set for the Set Problem(s)
    /// </summary>
    public class Set_E : ISet_E
    {

        public Set_E(string name, IEnumerable<IElement> elements, double cost, bool isFullSet)
        {
            this.Name = name;
            this.Elements = new HashSet<IElement>(elements);
            this.Cost = cost;           // if the cost is 0 it is the original full set!
            this.IsFullSet = isFullSet;
        }

        /// <summary>
        /// the list of IElements
        /// </summary>
        public HashSet<IElement> Elements { get; }

        /// <summary>
        /// the cost of the set
        /// </summary>
        public double Cost { get; }

        /// <summary>
        /// indicates whether the Set is the original full Set
        /// </summary>
        public bool IsFullSet { get; set; }

        /// <summary>
        /// name of the set
        /// </summary>
        public string Name { get; }

        IEnumerable<IElement> ISet_E.Elements
        {
            get
            {
                return this.Elements;
            }
        }

        /// <summary>
        /// readable representation of the set
        /// </summary>
        /// <returns>string</returns>
        public override string ToString() {
            var setName = this.Name + " with elements: ";
            foreach(var element in this.Elements)
            {
                setName = setName + element.Name + ", " ;
            }
            return setName;
        }

        /// <summary>
        /// indicates whether the given element is contained in this Set (true) or not (false)
        /// </summary>
        /// <param name="element"></param>
        /// <returns></returns>
        public bool ContainsElement(IElement element)
        {
            return this.Elements.Contains(element);
        }
    }
}

Program instance

Instantiation of the different Elements & Sets, the Model, as well as the Solver and an empty Solution. Program.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace SetProblems
{
    using System.Configuration;

    using OPTANO.Modeling.Common;
    using OPTANO.Modeling.Optimization;
    using OPTANO.Modeling.Optimization.Configuration;
    using OPTANO.Modeling.Optimization.Solver.Gurobi810;

    /// <summary>
    /// Demo program solving Set-problem(s)
    /// </summary>
    class Program
    {
        /// <summary>
        /// The main method
        /// </summary>
        /// <param name="args">
        /// no arguments required
        /// </param>
        static void Main(string[] args)
        {

            // create example elements
            IElement one = new Element("one", 1);
            IElement two = new Element("two", 2);
            IElement three = new Element("three", 3);
            IElement four = new Element("four", 4);
            IElement five = new Element("five", 5);

            // create full set
            ISet_E fullSet = new Set_E("full_set", 
                             new List<IElement> { one, two, three, four, five} , 0, true);

            // create subsets
            ISet_E subset_1 = new Set_E("subset_1", 
                              new List<IElement> { one, three }, 8, false);
            ISet_E subset_2 = new Set_E("subset_2", 
                              new List<IElement> { three, five }, 16, false);
            ISet_E subset_3 = new Set_E("subset_3", 
                              new List<IElement> { three }, 6, false);
            ISet_E subset_4 = new Set_E("subset_4", 
                              new List<IElement> { one, two, four }, 15, false);
            ISet_E subset_5 = new Set_E("subset_5",
                              new List<IElement> { one, five }, 7, false);

            var sets = new List<ISet_E>{subset_1, subset_2, subset_3, subset_4, subset_5};

            // Use long names for easier debugging/model understanding.
            var config = new Configuration();
            config.NameHandling = NameHandlingStyle.UniqueLongNames;
            config.ComputeRemovedVariables = true;
            using (var scope = new ModelScope(config))
            {

                // create a model, based on given data and the model scope
                var setProblemModel = new SetProblemModel(sets, fullSet);

                // Get a solver instance, change your solver
                using (var solver = new GurobiSolver())
                {
                    // solve the model
                    var solution = solver.Solve(setProblemModel.Model);

                    // import the results back into the model 
                    setProblemModel.Model.VariableCollections.ForEach(vc => vc.SetVariableValues(solution.VariableValues));

                    // print objective and variable decisions
                    Console.WriteLine($"{solution.ObjectiveValues.Single()}");
                    setProblemModel.y.Variables.ForEach(y => Console.WriteLine($"{y.ToString().PadRight(36)}: {y.Value}"));

                    setProblemModel.Model.VariableStatistics.WriteCSV(AppDomain.CurrentDomain.BaseDirectory);
                    Console.ReadLine();
                }
            }
        }
    }
}

Next Step

• Creating the Model