I'm a newbie so go easy.
I've been looking through the part 2 worked example in the Cade book and I'm unsure as to why the multiplicity of the Bid - Bidder association is different in the domain model on page 169 and the class diagram on page 172. In the domain model the relationship is that a bid can have one bidder but a bidder can have 0 to many bids whereas in the class diagram a Bid class is associated with 0 to many Bidder classes and the multiplicity from Bidder to Bid has gone. Is this a definite change or just a printing error? I thought it was a no no to change the given domain model like this? To me the relationship in the domain model makes sense so the change is confusing.