Does the ER model include Associative entities?
from my current understanding associative entities are only in the EER model, but my assignment is asking for associative entities in the ER model
Thanks in advance
I couldn't find any mention or description of associative entities in Chen's papers The Entity-Relationship Model - Toward A Unified View Of Data and The Entity-Relationship Model - A Basis For The Enterprise View Of Data. The earliest reference I found was in Codd's paper Extending The Database Relational Model To Capture More Meaning.
Song, Evans and Park explain in A Comparative Analysis of Entity-Relationship Diagrams that associative entities (aka gerunds) are a feature of binary data models, to handle many-to-many binary relationships, ternary and higher relationships, and attributes on relationships. Chen's Entity-Relationship model is an n-ary data model that can express these concepts directly, but associative entities still have a place in ER modeling to represent relationships that are subjects of other relationships. For example, see my answer to When to use Associative entities.
The latter paper also references Chen's The ER Designer: Reference Manual in relation to associative entities. Unfortunately, I don't have a copy of this paper and can't confirm whether Chen discussed the idea.
The ER model evolved and was extended multiple times, by other people as well as Chen. Associative entities were present in other data models at the time, and conflation of modeling disciplines was (and still is) common. In short, when exactly the idea formally entered (E)ER modeling isn't clear to me.
Based on Chen's two papers mentioned in my first paragraph, I suggest you exclude associative entities when using/discussing the original ER model.