Two cases must be considered:
If the average cardinality of the TARGET entity is different from 0, the key of the SOURCE entity is introduced as a redundant property into the logical entity coming from the TARGET conceptual entity. The properties possibly held by the relationship become the properties of the TARGET conceptual entity.
If the average cardinality of the TARGET entity is 0, the relationship is transformed into a logical entity. The key of this logical entity is the key of the TARGET entity. The key of the SOURCE entity is introduced as a redundant property into the created logical entity. The properties possibly held by the relationship become the properties of the logical entity created.
Example:
Analysis of the average cardinality of (0,1):
Average cardinality at 1: the key of the entity SUPPLIER (Supplier_code) is duplicated into the entity ITEM as a property of this file. The properties of the relationship (Unit_price and Delivery_time) are migrated into the entity ITEM.
Average cardinality at 0: the relationship PRICE becomes a logical entity, with the key of the entity ITEM (Item_code) as its key. The key of the entity SUPPLIER (Supplier_code) is duplicated into this entity as a property of this file.