<hibernate-mapping xmlns="urn:nhibernate-mapping-2.0" assembly="BLL" namespace="BLL">
<class name="Class1" table="table1">

<id name="Id" column="id" type="Int32" unsaved-value="0">
      <generator class="sequence">
        <param name="sequence">Class1_id_seq</param>
      </generator>
</id>   

<bag
     name="myList"
     access="field"
     inverse ="true"     
     cascade="all-delete-orphan">
      <key column ="id_table2"></key>
      <one-to-many class ="BLL.Class2,BLL" />
    </bag>


  </class>
</hibernate-mapping>

public class Class1    {
                private IList<Class2> myList;

public virtual IList<Class2> MyList
        {
            get
            {
                return myList;
            }
        }
}