/// <summary>
            /// Checks that only one role is played by the value type, that it has a boolean data type, and that
            /// if it has a value constraint, that value constraint is alethic and only allows the value 'true'.
            /// </summary>
            private static bool ValidateImplicitBooleanValueType(ObjectType implicitBooleanValueType)
            {
                if (!implicitBooleanValueType.IsValueType || !implicitBooleanValueType.IsImplicitBooleanValue || implicitBooleanValueType.IsIndependent ||
                    implicitBooleanValueType.PlayedRoleCollection.Count != 1 || !(implicitBooleanValueType.DataType is TrueOrFalseLogicalDataType))
                {
                    return(false);
                }

                ValueTypeValueConstraint valueConstraint = implicitBooleanValueType.ValueConstraint;

                if (valueConstraint != null)
                {
                    // UNDONE: We need to check for alethic here once ValueTypeValueConstraint supports Modality...
                    LinkedElementCollection <ValueRange> valueRangeCollection = valueConstraint.ValueRangeCollection;
                    ValueRange valueRange;
                    bool       value;
                    if (valueRangeCollection.Count != 1 ||
                        !bool.TryParse((valueRange = valueRangeCollection[0]).MinValue, out value) || !value ||
                        !bool.TryParse(valueRange.MaxValue, out value) || !value)
                    {
                        return(false);
                    }
                }
                else
                {
                    // UNDONE: We are only allowing open-world assumption for now, so the value constraint is required.
                    return(false);
                }

                return(true);
            }
            /// <summary>
            /// Binarizes the unary <see cref="FactType"/> specified by <paramref name="unaryFactType"/>, defaulting
            /// to using open-world assumption. The caller is responsible for making sure <paramref name="unaryFactType"/>
            /// is in fact a unary fact type.
            /// </summary>
            public static void BinarizeUnary(FactType unaryFactType, INotifyElementAdded notifyAdded)
            {
                Partition partition = unaryFactType.Partition;
                Store     store     = partition.Store;
                IHasAlternateOwner <FactType>      toAlternateOwner;
                IAlternateElementOwner <FactType>  alternateFactTypeOwner = (null == (toAlternateOwner = unaryFactType as IHasAlternateOwner <FactType>)) ? null : toAlternateOwner.AlternateOwner;
                LinkedElementCollection <RoleBase> roleCollection         = unaryFactType.RoleCollection;

                Debug.Assert(roleCollection.Count == 1, "Unaries should only have one role.");

                Role   unaryRole = (Role)roleCollection[0];
                string implicitBooleanValueTypeName = GetImplicitBooleanValueTypeName(unaryRole);

                // UNDONE: We are using open-world assumption now
                // Setup the mandatory constraint (for closed-world assumption)
                //MandatoryConstraint mandatoryConstraint = MandatoryConstraint.CreateSimpleMandatoryConstraint(unaryRole);
                //mandatoryConstraint.Model = unaryFactType.Model;
                //if (notifyAdded != null)
                //{
                //    notifyAdded.ElementAdded(mandatoryConstraint, true);
                //}

                // Setup the uniqueness constraint (to make the newly binarized FactType valid)
                if (unaryRole.SingleRoleAlethicUniquenessConstraint == null)
                {
                    UniquenessConstraint uniquenessConstraint = UniquenessConstraint.CreateInternalUniquenessConstraint(unaryFactType);
                    uniquenessConstraint.RoleCollection.Add(unaryRole);
                    if (notifyAdded != null)
                    {
                        notifyAdded.ElementAdded(uniquenessConstraint, true);
                    }
                }

                // Setup the boolean role (to make the FactType a binary)
                Role implicitBooleanRole = new Role(partition, null);

                implicitBooleanRole.Name = unaryRole.Name;

                // Setup the boolean value type (because the boolean role needs a role player)

                IAlternateElementOwner <ObjectType> alternateObjectTypeOwner = null;
                DomainClassInfo alternateCtor =
                    (null != alternateFactTypeOwner &&
                     null != (alternateObjectTypeOwner = alternateFactTypeOwner as IAlternateElementOwner <ObjectType>)) ?
                    alternateObjectTypeOwner.GetOwnedElementClassInfo(typeof(ObjectType)) :
                    null;
                PropertyAssignment implicitBooleanProperty  = new PropertyAssignment(ObjectType.IsImplicitBooleanValueDomainPropertyId, true);
                ObjectType         implicitBooleanValueType = (alternateCtor != null) ?
                                                              (ObjectType)partition.ElementFactory.CreateElement(alternateCtor, implicitBooleanProperty) :
                                                              new ObjectType(partition, implicitBooleanProperty);
                Dictionary <object, object> contextInfo = store.TransactionManager.CurrentTransaction.TopLevelTransaction.Context.ContextInfo;
                object duplicateNamesKey         = ORMModel.AllowDuplicateNamesKey;
                bool   removeDuplicateNamesKey   = false;
                object duplicateSignaturesKey    = ORMModel.BlockDuplicateReadingSignaturesKey;
                bool   addDuplicateSignaturesKey = false;

                try
                {
                    if (!contextInfo.ContainsKey(duplicateNamesKey))
                    {
                        contextInfo[duplicateNamesKey] = null;
                        removeDuplicateNamesKey        = true;
                    }
                    if (contextInfo.ContainsKey(duplicateSignaturesKey))
                    {
                        contextInfo[duplicateSignaturesKey] = null;
                        addDuplicateSignaturesKey           = true;
                    }
                    implicitBooleanValueType.Name = implicitBooleanValueTypeName;
                    if (alternateCtor != null)
                    {
                        ((IHasAlternateOwner <ObjectType>)implicitBooleanValueType).AlternateOwner = alternateObjectTypeOwner;
                    }
                    else
                    {
                        implicitBooleanValueType.Model = unaryFactType.ResolvedModel;
                    }
                    if (notifyAdded != null)
                    {
                        notifyAdded.ElementAdded(implicitBooleanValueType, true);
                    }
                }
                finally
                {
                    if (removeDuplicateNamesKey)
                    {
                        contextInfo.Remove(duplicateNamesKey);
                    }
                    if (addDuplicateSignaturesKey)
                    {
                        contextInfo[duplicateSignaturesKey] = null;
                    }
                }
                implicitBooleanValueType.DataType = store.ElementDirectory.FindElements <TrueOrFalseLogicalDataType>(false)[0];

                // Set value constraint on implicit boolean ValueType for open-world assumption
                ValueTypeValueConstraint implicitBooleanValueConstraint = implicitBooleanValueType.ValueConstraint
                                                                              = new ValueTypeValueConstraint(partition, null);

                // Add the true-only ValueRange to the value constraint for open-world assumption
                implicitBooleanValueConstraint.ValueRangeCollection.Add(new ValueRange(partition,
                                                                                       new PropertyAssignment(ValueRange.MinValueDomainPropertyId, bool.TrueString),
                                                                                       new PropertyAssignment(ValueRange.MaxValueDomainPropertyId, bool.TrueString)));

                // Make the boolean value type the role player for the implicit boolean role
                implicitBooleanRole.RolePlayer = implicitBooleanValueType;

                // Add the boolean role to the FactType
                roleCollection.Add(implicitBooleanRole);
                if (notifyAdded != null)
                {
                    notifyAdded.ElementAdded(implicitBooleanRole, true);
                }
            }