A.D&D.Sci May 2021: Interdimensional Monster Carcass Auction
You are the most successful butcher in your tiny, snow-swept village. You’re just about to close up shop when a man appears from an interdimensional portal and offers to sell you carcasses from a distant timeline.
You’d be more perturbed, but you live and work in a village frequented by Adventurers; this is maybe the second- or third-weirdest thing you’ve had to deal with this month. Instead of panicking, you calmly and logically inquire as to how you could possibly evaluate the value of such oddities.
The stranger smiles, tells you you always say that, and offers you a record (written in what is unmistakably your handwriting) telling you how much money your parallel-universe doppelgangers made when he sold them a batch of dead things.
Finding this to be in order, you prepare to begin negotiations. The man smiles again, confesses he’s found himself to be a much worse salesman than you are a haggler, and instead proposes a sealed-bid auction, like the ones you remember from your apprenticeship. When you accept, he conjures three versions of you from neighbouring timelines and tells you all to get bidding.
(In case the subtext isn’t clear: yes, this challenge will be pitting you against your fellow LessWrongers.)
The available lots are as follows:
| Lot Number | Species | Days Since Death |
| #1 | Red Dragon | 1 |
| #2 | Jungle Mammoth | 1 |
| #3 | Mild Boar | 5 |
| #4 | Jungle Mammoth | 5 |
| #5 | Mild Boar | 1 |
| #6 | Green Dragon | 2 |
| #7 | Mild Boar | 2 |
| #8 | Mild Boar | 5 |
| #9 | Mild Boar | 8 |
| #10 | Mild Boar | 6 |
| #11 | Mild Boar | 8 |
| #12 | Blue Dragon | 8 |
| #13 | Jewel Beetle | 1 |
| #14 | Mild Boar | 1 |
| #15 | Jungle Mammoth | 4 |
| #16 | Jungle Mammoth | 2 |
| #17 | Mild Boar | 5 |
| #18 | Red Dragon | 6 |
| #19 | Mild Boar | 5 |
| #20 | Jungle Mammoth | 1 |
You have 300 silver pieces to hand. So does the competition. How will you bid?
Notes:
Payments are collected in lot order; if you’re unable to pay your bid by the time a given lot comes up, you lose your claim to that lot but incur no penalty.
Matching bids will be resolved randomly.
One entry per player, please.
If I get more than four entries, I’ll split the game into multiple universes; and if I get a number of entries not divisible by four, I’ll fill the empty spots with NPCs: no matter what happens, you’ll definitely be bidding against three opponents.
As a prize, the player who makes the most profit gets to specify one non-ridiculous thing about July’s D&D.Sci challenge. (Note that by my standards, “it must centre on a talking penguin called Steve” is much less ridiculous than “it must not involve any selection bias”.)
Once you’ve made your decisions, DM me (if for some reason you’re averse to having a LessWrong account, my email is abstraction dot application at protonmail dot com). The deadline for submissions is midnight Sunday BST.
I’ll be posting who won, along with an explanation of how I generated the dataset, sometime next Monday. I’m giving you a week, but the task shouldn’t take more than a few hours; use Excel, R, Python, Post-Metarationality, or whatever other tools you think are appropriate. Let me know in the comments if you have any questions about the scenario. (You probably shouldn’t use the comments for anything else, unless you feel like tipping your hand to potential opponents)
Initial thoughts:
Mild Boar is the best name I’ve seen in a while.
We’re bidding against other people, not against essentially-us, as the problem initially states. :D
I wonder how good the NPCs are? If e.g. there are 6 PCs, it should be two groups of 3 apiece with an extra NPC thrown into each group.
How concerned should we be that this man’s best available method of making money off of his carcasses is to create a portal to 4 alternate dimensions???? Also, from a distant timeline? I am disturbed, not at the existence of an interdimensional traveler, but at the implications that this is his efficient path.
Regarding PCs & NPCs: My plan for handling the NPCs is pretty much as you said; if I end up needing multiple worlds, I’ll make sure the human players are distributed as close to evenly as possible.
Regarding the premise: Being better at interdimensional travel than at regular teleportation produces some weird incentives. Also, magic-users are generally understood to be crazy; “that mage is doing something unusual!” is about as concerning as “that fire is hot!”
My first thought was that if I’m bidding against different versions of me then we should all co-operate and bid at most 1sp in order to maximise our profits. However we would most likely be up against NPC who won’t do this which wrecks this strategy. In the absence of any indicateion of how the NPC and other bidders would bid I generated a random price between 0.9* average price and 0.9* minimum price, and then manually adjusted a couple that didn’t look right which resulted in the following bids:
Lot 1 Red Dragon 1 days since killed 73sp
Lot 2 Jungle Mammoth 1 days since killed 35sp
Lot 3 Mild Boar 5 days since killed 14sp
Lot 4 Jungle Mammoth 5 days since killed 22sp
Lot 5 Mild Boar 1 days since killed 14sp
Lot 6 Green Dragon 2 days since killed 63sp
Lot 7 Mild Boar 2 days since killed 16sp
Lot 8 Mild Boar 5 days since killed 7sp
Lot 9 Mild Boar 8 days since killed 5sp
Lot 10 Mild Boar 6 days since killed 10sp
Lot 11 Mild Boar 8 days since killed 2sp
Lot 12 Blue Dragon 8 days since killed 18sp
Lot 13 Jewel Beetle 1 days since killed 4sp
Lot 14 Mild Boar 1 days since killed 14sp
Lot 15 Jungle Mammoth 4 days since killed 29sp
Lot 16 Jungle Mammoth 2 days since killed 29sp
Lot 17 Mild Boar 5 days since killed 10sp
Lot 18 Red Dragon 6 days since killed 44sp
Lot 19 Mild Boar 5 days since killed 14sp
Lot 20 Jungle Mammoth 1 days since killed 34sp
I’m assuming that BST is British Summer Time and the deadline has passed. Remarks about the problem and my bid before abstractapplic posts the results:
Decision on how aggressively to bid
With some exceptions for the jewel beetle and mild boars, discussed below, I generally estimated the EV and bid lower by a scaling factor. The scaling factor was pretty ad hoc and not based on some sophisticated game theory, as I don’t really know how aggressively people are going to bid. I did not adjust the scaling factor based on the lot number.
One Schelling point is to bid a total of 300, so I figure I should probably bid higher than that on average (given the revenue up for grabs is more than twice that). Another would be to bid at the minimum end of the observed range for each lot, so I could have tried to beat that if the minimums were reasonable, but didn’t get around to actually checking this, except that I did note that my bids were above my expectations for what the true minimums were in the cases where I got around to estimating that.
I assume other people are also bidding above these points. If that is not the case, I will win a lot of bids, but likely lose in profit to someone making higher per-lot profit on fewer lots.
Analysis of revenue from different carcass types:
Jungle Mammoths:
The Jungle Mammoths (=elephants?) looked consistent with a formula of 31+4d6-3dsd so I assumed that their EV was 45-3dsd.
Dragons:
The dragons look like they all have similar characteristics in their drops over time, with in particular a big drop of around 30 value between 4 and 5 dsd (except gray dragon which has too little data to tell). One possibility would be that each has their own non-time variant distribution which is added with a “dragon curve”. If I had more time, I would have tried to figure out the dragon curve and the separate distributions based on comparing the different dragon types (or rule it out and look for another hypothesis). As it is, I estimated the dragons in a pretty ad-hoc manner (eyeballing graphs mostly).
I do note that red dragon has some interesting even/odd behaviour, as it is always odd from 1 dsd to 6 dsd, and always even from 7 dsd to 10 dsd. If the “dragon curve” hypothesis is true, then this could be explained by an always-even or always odd “red distribution” (e.g. 2*2d12?) combined with a “dragon curve” that switches from odd to even at that point.
Mild boars:
For the mild boars (=pigs?), I tried to figure some model out that would match the observed qualitative behaviour and came up with rolling two d20s and setting each individually to 0 if less than or equal to the dsd. However, this did not match the quantitative characteristics, as it was consistently too pessimistic at low dsd and too optimistic at high dsd.
So, instead of taking the hint that I was wrong, I doubled down and added some epicycles. Namely, rolling 3 dice, setting each to zero if below dsd, then taking the top two, except that if you rolled a zero, you had to include the zero. (That’s a pretty crazy hypothesis as stated, but maybe slightly less crazy in the equivalent formulation of adding the dsd to each die, taking the top two dice, and then setting any die over 20 to zero).
This seemed to predict the low-dsd mild boars a lot better, but was still optimistic on the high-dsd mild boars. Due to low numbers, a close fit on the high-dsd boars might be less necessary though. It also predicts a bimodal distribution with a trough at around 22 and while you can sort of see something like a hint of that in the data, it is not very convincing. Going to 4 dice adversely affected the early mild boar fit and seemed worse overall.
Anyway, I decided to roll with it (the 2 out of 3 d20s model), but since I am not super convinced, I limited my bids on the 8 dsd mild boars (lots 9 and 11) to 9sp, equal to the ceiling of the average of observed value for 8 dsd mild boars. Due to the “winner’s curse”, in the very likely event that I am wrong on their distribution I will probably take a loss on these.
Jewel Beetle
As previously remarked on by other commenters, the jewel beetle (or “lottery ticket beetle” as I think of it) has a high variance distribution. It looks more or less like a power law. In fact, it looks like it’s such an extreme power law that it won’t even have a finite expected value, as the extreme low frequency outliers will have value disproportionate to the low frequency.
So, if I were in the position of the hypothetical scenario provided, I would probably bid a lot for the lottery ticket beetle.
However, I’m not in that situation. I am instead competing for the glory of being Numbah One. And while the jewel beetle might have an extreme value, it probably doesn’t. So, I reduced my jewel beetle bid to the median jewel beetle value of 12 instead of gambling on an outlier here.
I also note that new jewel beetles seem to tend to be lower in value than old ones. Not sure if this is random and my prior is generally against this.
Actual Bid
71,33,16,24,20,51,19,16,9,15,9,18,12,20,26,31,16,42,16,33
The “Mild Boar and Jungle Mammoth are just what the person from the Harsh Survivalist Ice Village calls pigs and elephants” speculation is hilarious and I wish I’d done that on purpose; I hereby retroactively declare it canon.
I have submitted a bid. If this is useful information that you can use, congratulations.
Beetle hands! NPCs will all bid 300 on the beetle, I assume. HODL!
Is Row 173 accurate? It’s really far away from all the other numbers.
173,Jewel Beetle,9,2514sp
Yes.
Is our profit evaluated based on actual results, or based on expected value?
Actual results.
If there are multiple universes, will the actual lot values be independent draws/rolls in each universe or one draw/roll for all universes?
One roll for all universes.