============================================================================== Part B

List of Relations

• Item (id, name, buyPrice, firstPrice, started, ends, sellerId, description)
  • key: {id}
• ItemCategory (itemId, category)
  • key: {itemId, category}
• AuctionUser (id, isSeller, isBidder, rating, location, country)
  • key: {id}
• Bid (itemId, bidderId, bidTime, price)
  • key: {itemId, bidderId, bidTime} -- one bidder can only bid for one item at each given time -- however, the document does not rule out the possiblity that a user account bid on different item at the same time

List of completely nontrivial functional dependencies

• Item
  • none if excluding {id}->{all other attributes}
• ItemCategory
  • none, since all attributes combined forms key
• AuctionUser
  • none if excluding {id}->{all other attributes}
• Bid
  • none if excluding {itemId, bidderId, bidTime} -> {price}

BCNF

• All the relations are in BCNF.

List of nontrivial multivalued dependencies

• Item
  • none
• ItemCategory
  • none
• AuctionUser
  • none
• Bid
  • none

4NF

• All the relations are in 4NF.

For coming project parts: extension approach once online

• Enter bids on items
  • require bidder id
  • check Item about auction end time
  • insert new entry in Bid
• Close auction
  • identify bidder id and item id
  • determine bid winner
  • design scheme to automatically close auction upon end time
  • maybe allow seller optionally close auction before end time
• Add new user
  • insert new entry in AuctionUser, make sure no duplicate id
  • ask user's interest in being seller/bidder/both
  • initialize rating to 0
• Add new auction
  • auto generate auction id
  • require user to fill in necessary information