public class Policy
{
    public int Id { get; set; }
    public int EntityId { get; set; }
    public int ProgramId { get; set; }

    public string PolicyNumber { get; set; }
    public DateTime EffectiveDate { get; set; }
    public DateTime ExpirationDate { get; set; }

    public virtual Entity Entity{ get; set; }
    public virtual Program Program { get; set; }
    public virtual ICollection<Transaction> Transactions { get; set; }
}

public sealed class PolicyMapper : ClassMapper<Policy>
{
    public PolicyMapper()
    {
        Map(p => p.Entity).Ignore();
        Map(p => p.Program).Ignore();
        Map(p => p.Transactions).Ignore();
        AutoMap();
    }
}

public sealed class PolicyMapper : ClassMapper<Policy>
{
    public PolicyMapper()
    {
        IgnoreAllVirtual();
        AutoMap();
    }
}