interface IFactory<TConfiguration,TProblem>
          where TProblem: IProblem
          where TConfiguration: IConfiguration
{
   TProblem Create(TConfiguration config);
}

class Factory<TConfiguration,TProblem>: IFactory<TConfiguration,TProblem>
          where TProblem: IProblem
          where TConfiguration: IConfiguration
{
   TProblem Create(TConfiguration config)
   {
       var problem = new Problem(config);
       ...
       return problem;
   }
}