public List<decimal> GetRatings(Alternative alternative)
 {
     return Items.Where(x => x.AlternativeId == alternative.AlternativeId).OrderBy(x => x.FactorId).Select(x => x.Rating.Value).ToList();
 }
 public List<decimal> GetWeights(Alternative alternative)
 {
     return Items.Where(x => x.AlternativeId == alternative.AlternativeId).OrderBy(x => x.FactorId).Select(x => x.Weight).ToList();
 }
 public List<decimal> GetProbabilities(Alternative alternative)
 {
     return Items.Where(x => x.AlternativeId == alternative.AlternativeId).OrderBy(x => x.FactorId).Select(x => x.Probability.Value).ToList();
 }