/// <summary>
        /// Perform a multi-point crossover.
        /// </summary>
        protected override IList<ICell> Reproduce(ICell actor, ICell target)
        {
            if (actor == null) throw new ArgumentNullException("actor");
            if (target == null) throw new ArgumentNullException("target");

            // Percentage of each tag crossing over is normalized to produce one
            // cross on average by default.  This is modified by the CrossoverFactor.
            int crossoverPercent = (int) (100 / actor.ActiveTagsInModel * CrossoverFactor);

            ICell child1 = actor.CreateEmptyCell();
            ICell child2 = actor.CreateEmptyCell();

            for (int i = 0; i < actor.ActiveTagsInModel; i++)
            {
                if (RandomProvider.Next(100) < crossoverPercent)
                {
                    Tag actorTag = actor.GetTagByIndex(i);
                    Tag targetTag = target.GetTagByIndex(i);

                    Tag childTag1 = null;
                    Tag childTag2 = null;

                    CrossoverInteraction.CrossOverTags(actorTag, targetTag, out childTag1, out childTag2);

                    child1.SetTagByIndex(i, childTag1);
                    child2.SetTagByIndex(i, childTag2);
                }
                else
                {
                    child1.SetTagByIndex(i, Tag.New(actor.GetTagByIndex(i)));
                    child2.SetTagByIndex(i, Tag.New(target.GetTagByIndex(i)));
                }
            }

            if (AllowMutation)
            {
                PointMutation.Mutate(child1);
                PointMutation.Mutate(child1);
            }

            return new List<ICell>() { child1, child2 };
        }
        /// <summary>
        /// Perform a single point crossover.
        /// </summary>
        protected override IList<ICell> Reproduce(ICell actor, ICell target)
        {
            if (actor == null) throw new ArgumentNullException("actor");
            if (target == null) throw new ArgumentNullException("target");

            // Select the tag to crossover
            int crossoverIndex = RandomProvider.Next(0, actor.ActiveTagsInModel - 1);

            // Create two new cells like this (assuming crossover in tag 3):
            //
            // AAAA AAAA AATT TTTT
            // TTTT TTTT TTAA AAAA

            ICell child1 = actor.CreateEmptyCell();
            ICell child2 = actor.CreateEmptyCell();

            for (int i = 0; i < actor.ActiveTagsInModel; i++)
            {
                if (i < crossoverIndex)
                {
                    child1.SetTagByIndex(i, Tag.New(actor.GetTagByIndex(i)));
                    child2.SetTagByIndex(i, Tag.New(target.GetTagByIndex(i)));
                }
                else if (i > crossoverIndex)
                {
                    child1.SetTagByIndex(i, Tag.New(target.GetTagByIndex(i)));
                    child2.SetTagByIndex(i, Tag.New(actor.GetTagByIndex(i)));
                }
                else // i == crossoverIndex
                {
                    // There are length+1 crossover points for a Tag (start, end, length-1 midpoints)
                    Tag actorTag = actor.GetTagByIndex(i);
                    Tag targetTag = target.GetTagByIndex(i);

                    Tag childTag1 = null;
                    Tag childTag2 = null;

                    CrossOverTags(actorTag, targetTag, out childTag1, out childTag2);

                    child1.SetTagByIndex(i, childTag1);
                    child2.SetTagByIndex(i, childTag2);
                }
            }

            if (AllowMutation)
            {
                PointMutation.Mutate(child1);
                PointMutation.Mutate(child1);
            }

            return new List<ICell>() {child1, child2};
        }