MS Solver Foundation CSP Error - Inputs have different Symbol Domain

Question

I am trying to use Microsoft Solver Foundation to solve our family Christmas draw (similar to a "secret santa" or "kris kringle").

I have some complex constraints (e.g can't buy for your siblings), which I have already used to prune the domains for each participant.

The solver works, except that it doesn't have a constraint that a person should only receive one present (i.e. Alice buying for Bob implies that no-one else is buying for Bob).

I tried adding a "AllDifferent" constraint, but am getting an Argument Exception-

"Inputs Alice and Bob have different symbol domains."

I also tried adding the constraint as a OML expression, but ran into the same error.

Is it possible to apply any constraints between decisions with different domains?
If not, and I need to use the same domain for all decisions, is there a "contains" constraint? (I tried to use "ElementOf" but was unable to get it to work.)

Sample program-

using System;
using System.Collections.Generic;
using System.Linq;
using Microsoft.SolverFoundation.Services;

namespace XmasDrawCSP
{
    public class Class1
    {
        public static void Main(string[] args)
        {

            SolverContext context = SolverContext.GetContext();
            Model model = context.CreateModel();

            Dictionary<string, string[]> PossiblyBuysFor = new Dictionary<string, string[]>();

            //Alice and Carol are sisters
            //Bob and David are brothers

            //Can't buy for siblings or yourself
            PossiblyBuysFor["Alice"] = new string[] { "Bob", "David", "Eve", };
            PossiblyBuysFor["Bob"] = new string[] { "Alice", "Carol", "Eve", };
            PossiblyBuysFor["Carol"] = new string[] { "Bob", "David", "Eve", };
            PossiblyBuysFor["David"] = new string[] { "Alice", "Carol", "Eve", };
            PossiblyBuysFor["Eve"] = new string[] { "Alice", "Bob", "Carol", "David", };

            foreach (var giver in PossiblyBuysFor.Keys)
            {
                Decision d = new Decision(Domain.Enum(PossiblyBuysFor[giver]), giver);
                model.AddDecision(d);
            }

            //Error thrown here- "Inputs Alice and Bob have different symbol domains."
            model.AddConstraint("one_present_each", Model.AllDifferent(model.Decisions.ToArray()));

            Solution solution = context.Solve(new ConstraintProgrammingDirective());

            int i = 0;
            while (solution.Quality != SolverQuality.Infeasible && i < 10)
            {
                Console.WriteLine(i);

                foreach (var d in solution.Decisions)
                {
                    Console.WriteLine(string.Format("{0} buys for {1}", d.Name, d.ToString() ));
                }

                Console.ReadLine();
                solution.GetNext();
                i++;
            }

            Console.ReadLine();
        }
    }   
}

score -1 · Answer 1 · answered Apr 02 '14 at 13:28

I've found a solution. I use the same domain for all decisions, and then add the restricted domain as constraint.

I was confusing myself by having decision names the same as the solution values.

It's a bit messy, but here is the working solution-

using System;
using System.Collections.Generic;
using System.Linq;
using Microsoft.SolverFoundation.Services;

namespace XmasDrawCSP
{
    public class Class1
    {

        public static void Main(string[] args)
        {

            var Names = new string[] { 
                "Alice", "Bob", "Carol", "David", "Eve",
            };

            Domain Recipients = Domain.Enum(Names);

            SolverContext context = SolverContext.GetContext();
            Model model = context.CreateModel();

            Dictionary<string, string[]> PossiblyBuysFor = new Dictionary<string, string[]>();

            //Alice and Carol are sisters
            //Bob and David are brothers

            //Can't buy for siblings or yourself
            PossiblyBuysFor["Alice"] = new string[] { "Bob", "David", "Eve", };
            PossiblyBuysFor["Bob"] = new string[] { "Alice", "Carol", "Eve", };
            PossiblyBuysFor["Carol"] = new string[] { "Bob", "David", "Eve", };
            PossiblyBuysFor["David"] = new string[] { "Alice", "Carol", "Eve", };
            PossiblyBuysFor["Eve"] = new string[] { "Alice", "Bob", "Carol", "David", };

            foreach (var giver in PossiblyBuysFor.Keys)
            {
                Decision d = new Decision(Recipients, giver.ToLower());
                model.AddDecision(d);   
            }

            foreach (var giver in PossiblyBuysFor.Keys)
            {
                string term = "1 == 0 ";
                foreach (var valid in PossiblyBuysFor[giver])
                {
                    term += string.Format(" | {0} == \"{1}\"", giver.ToLower(), valid);
                }

                model.AddConstraint("domain_restriction_" + giver, term); 
            }

            model.AddConstraint("one_present_each", Model.AllDifferent(model.Decisions.ToArray()));

            Solution solution = context.Solve(new ConstraintProgrammingDirective());



            int i = 0;
            while (solution.Quality != SolverQuality.Infeasible && i < 10)
            {
                Console.WriteLine(i);

                foreach (var d in solution.Decisions)
                {

                    Console.WriteLine(string.Format("{0} buys for {1}", d.Name, d.ToString()));
                }

                Console.ReadKey();
                solution.GetNext();
                i++;
            }
            Console.WriteLine("The end");
            Console.ReadKey();

        }

MS Solver Foundation CSP Error - Inputs have different Symbol Domain

1 Answers1