Exercise $4\mathrm{.}46$ Create an auction with a few lots, persons, and bids. Then use the object inspector to investigate the object structure. Start with the auction object, and continue by inspecting any further object references you encounter in the objects' fields.

$4\mathrm{.}14$ Another example: an auction system

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Because neither the Person class nor the Bid class initiates any activity within the auction system, we shall not discuss them here in detail. Studying these classes is left as an exercise to the reader. Instead, we shall focus on the source code of the Lot and Auction classes.