Matthew Hayward wrote:
David Zych wrote: Forking a new thread from
truedungeon.com/forum?view=topic&defaultmenu=141&catid=584&id=250328&start=48#353987
I agree with Wade, and I'll try to fill in the details of why.
Imagine a very faithful, very patient virtual assistant to whom you have given the instructions "Try to win 17 PYPs at the lowest price you can. Don't pay more than $105 each." This assistant uses that information to place actual bids for individual items on your behalf, one at a time. Every bidder has such an assistant, and the assistants do not share knowledge with each other.
In my opinion, the appropriate auction result is the one that is consistent with this model. Of course there are implementation shortcuts available, but to see how the model works, let's walk through all the actual bids which result deterministically from the application of B's bid.
Initially A bids $0.25 on PYP#1-17:
PYP#1-17 A $0.25
PYP#18-32 $0
1. B bids $0.25 on PYP#18-32.
PYP#1-17 A $0.25
PYP#18-32 B $0.25
...snip...
Here is what I think you're doing, is equivalent to can you tell me if it amounts to the same thing?
1. Take all the bid amounts and quantities, and at the end of the bidding period:
2. Run a virtual auction for each identical item sequentially, one at a time, using eBay rules, removing the winning bids from the bid pool at the start of the subsequent auction.
That's definitely not what I'm doing. I am running all 32 auctions at the same time, so that each virtual assistant can place its next actual bid on whichever item happens to be going for cheapest at that moment. None of the auctions is over until all virtual assistants have stopped bidding.
If so, consider what happens in this scenario:
There are 2 identical items available.
A bids first and wants 1 item at $105 or less
B bids second and wants 1 item at $100 or less
C bids third wants 1 item at $1 or less
Great example! Much easier to follow than 32 items.
Here's the step by step breakdown at Auction House Lambda:
1. A bids $0.25 on item 1. A is happy.
2. B bids $0.25 on item 2. B is happy.
At this point A and B are winning one item each for $0.25
3. C bids $0.50 on item 1 (outbidding A).
4. A bids $0.25 on item 2 (displacing B, since early bids win ties).
5. B bids $0.50 on item 2 (outbidding A).
6. A bids $0.50 on item 1 (displacing C, since early bids win ties).
At this point A and B are winning one item each for $0.50
7. C bids $0.75 on item 1 (outbidding A).
8. A bids $0.50 on item 2 (displacing B, since early bids win ties).
9. B bids $0.75 on item 2 (outbidding A).
10. A bids $0.75 on item 1 (displacing C, since early bids win ties).
At this point A and B are winning one item each for $0.75
11. C bids $1 on item 1 (outbidding A).
12. A bids $0.75 on item 2 (displacing B, since early bids win ties).
13. B bids $1 on item 2 (outbidding A).
14. A bids $1 on item 1 (displacing C, since early bids win ties).
At this point A and B are winning one item each for $1.
15. C gives up. A and B win for $1 each.
Hopefully this helps you see my conceptual model. You'll notice that in this simple case, Auction House Lambda and Auction House Beta end up with the same answer.
Now suppose D wants one item at $110. At Auction House Lambda, D will bid both A and B up to $100, one increment at a time (just like C did), then bid $105 on item 1 (outbidding A). A bids $100 on item 2 (displacing B ), and B gives up.
Result: D wins for $105 and A wins for $100.
Auction House Beta would knock D's price down to $100 as well. That's good news (at least in the short term) if you're D. But I see three comparative downsides:
First, if I'm B, this result doesn't sit quite right. Shouldn't somebody who bids
after me need to actually pay
more than I was willing to pay in order to win the item I wanted? That's not a deal-breaker as long as the rules were stated clearly up front, but IMO it's a consideration.
Second, Auction House Beta ends up taking in $5 less. Running an auction house is hard work! If there are two generally reasonable sets of rules to choose from, I certainly won't begrudge the auction house choosing the one that nets them a little bit more in the end. I'm grateful there are auction houses available so I don't have to pay $250 for my PYPs.
Third, Auction House Beta offers less incentive for early bidding compared to Auction House Lambda. Early bidding helps auctions to succeed, and we all (bidders and auction house managers alike) want TD auctions to succeed.