Someone asked me to do a guide on chaining dummy items, and since this is one of the most confusing aspects about math trades, I figured I'll just do a guide on all of duplicate protection in the OLWLG, with the advanced bits at the end.
- How to set everything up
- What's happening here?
Common extensions of duplicate protection
- You only want one of two different games
- Managing money wants with dummies
- You only want one of two different games (the easy way)
- Managing money wants with dummies (the easy way)
- You only want to trade one of two games away
- Duplicate protection for more than one copy of a game
- You value many or all of your games equally
How to turn these charts into wantlists
Sometimes, the same game is offered by more than one person. More likely than not, you'll want to add both entries to your want list to increase your chances of getting at least one of them. With duplicate protection, you can make sure that you won't receive the same game twice, even if you add more than one of it to your want lists.
First, let's take a look at how to set this up:
1) In the OLWLG, go to "Step 4". Wow, seems I already have bunch of items in my want list. To keep things simple, we'll focus only on duplicate protection for the two copies of "Robinson Crusoe: Adventures on the Cursed Island".
2) Click the button "Duplicate Protection" that can be found both at the top and at the bottom of the page. You'll get to a page similar to this:
3) We'll start by "Creating dummies the easy way". For that, we'll use the table in the lower half of the page. Normally, I would check all of the checkmarks in that list because I want all of the games to have duplicate protection. For this tutorial, I'll only check Robinson Crusoe though.
Note also the checkmark at the bottom of the list. This is set by default and you pretty much always want to leave it set. With this checkmark, if I were to add another copy of Robinson Crusoe later on, it will automatically be added to the dummy item.
Once you have selected everything you need, hit "Submit".
4) As you can see, the table from Step 4 has changed a bit. The two copies of Robinson Crusoe now have a gray background, because they're covered by a dummy item. There's also a new row and a new column "Robinson Crusoe: Adventures on the Cursed Island", both with a green background. These refer to the dummy item and are really one and the same. Finally, there are checkmarks already set at the intersection between the old Robinson Crusoe items and the column for our new dummy item.
5) Now how do we select our wants for Robinson Crusoe? It's really quite simple: For every column where you normally would have set a checkmark for the Robinson Crusoe listings, you now set one only for the row with the dummy item. This is very important: Do not set new checkmarks in the greyed out row with the original items or the duplicate protection could fail.
Remember to hit "Confirm Changes" at the bottom of the page after you've set your checkmarks.
Now, what has happened here?
Without duplicate protection, your trade wishes could be put into a chart like this: Everything you want in the trade is on the left side and everything you want to trade away is on the right. Arrows indicate which of your wants you would accept for which of your haves. In this case, you have marked all four possible trades as acceptable.
As you can see, it is easy to find two trades in here, resulting in you getting both copies of Robinson Crusoe:
However, with duplicate protection, you have created a dummy item that sits in the middle. It both accepts all copies of Robinson Crusoe, and offers to the games that you wanted to trade away. There's also only one copy of the dummy item, so it can only be part of one trade.
Now, if a trade is found with the dummy item, that's the only trade the dummy can be part of, even if it still has other items that it accepts or offers to. Since the listings for Robinson Crusoe can only go through the dummy item, and that can't be part of more than one trade, you can be sure that you'll only get one copy of the game.
Finally, if, in this guide, you ever find yourself wondering how to translate one of these charts into checkmarks for the table in Step 4:
- Create a dummy item for every circle in the chart.
- Set the checkmark at an intersection of two items for each arrow in the chart. The pointy end of the arrow is the column, the round end is the row.
Common extensions of duplicate protection
You only want one of two different games
Let's say you have both Suburbia and Castles of Mad King Ludwig on your want list, but you only want one of the two because you've heard that they're similar to each other. This sounds like a job for duplicate protection, but the dummy items we've created so far only work if it's the exact same game.
Let's go back to step 2), right after we clicked "Duplicate Protection"
This time though, instead of "creating them the easy way", we'll use the form at the top.
- The first field "Short Identifier" is just an id that is primarily for the system. It doesn't hurt to make this recognizable, but you won't really see it.
- The second field "Short description" is the name of the dummy item as it will appear in the big table from Step 4. Make sure that it's easily recognizable to you.
- We'll get to the checkmark in the next example, leave it unchecked for now.
- Once you've filled everything in, hit "Create". Try to not hit that button or the Enter key before all the info is correct. If you make a mistake, you can of course leave the wantlist for the incorrect dummy empty and everything will work just fine; but you can't delete dummy items and it'll sit there, mocking you.
Once you're back on the big table, you'll have to set the checkmarks that previously were automatically filled in yourself. Go to each row containing either Suburbia or Castles of Mad King Ludwig and check the box at the intersection with the column of the new dummy item. (sorry, no screenshots for this since the example isn't actually in my wantlist)
After that, you can set the other checkmarks just like you did in the basic example.
The result is a trade chart very similar to that of normal duplicate protection. The only difference is that, this time, two different games are wanted by a single dummy item.
Managing money wants with dummies
You may have already noticed, but when there are many offers for the same game, it's much easier to set the checkmarks once for the dummy item instead of over and over for every single offer. This could be very useful for handling all those money listings, but the problem is, you don't actually mind getting money several times. This is were non-duplicate protected dummies come in.
Let's go back to step 2) and, just like last time, create a dummy item using the form at the top of the page. This time though, do set the checkmark "Non-duplicate …". This checkmark signifies that you don't mind getting several of the items contained in this dummy item.
Repeat this a few times until you have dummies for all ranges of money you need. And, again, set the checkmarks at the intersections between the row of the money offers and the column of their respective money dummy item.
This time, the chart is a bit different, so let's take a look:
First off, this is the first example with more than one dummy item, but that is pretty straightforward. The interesting change is that the dummy items this time have an unlimited supply, i.e. they can be part of more than one trade as long as they have both things they want and things they offer to connected to them. Simply put:
Finally, let me introduce you to chaining. Chained dummy items are dummies, that are themselves again part of other dummies, and they turn the duplicate protection into a pretty flexible way of managing your wants (though no, afaik you still can't value items in a dummy differently).
To set up such a chain, you will need to set checkmarks at the intersection between two dummy items. At that point, the OLWLG will display a warning that "This is not normally something you want to to". You can safely click OK on that.
Good news, everyone! JeffyJeff was so kind to confirm that chaining definitely works. (Those that were here before may recall a disclaimer that I'm only 99% sure.) To celebrate, I've added a whole new section to the guide on how to turn these charts into olwlg wantlists as well as a new example for chaining.
You only want one of two different games (the easy way)
Remember how you wanted to get either Suburbia or Castles of Mad King Ludwig? Now, what if each of those has 3 different listings? Adding every single listing to the dummy item sounds way too tedious. Instead, automatically generate dummies for Suburbia and CoMKL with "Create dummy items the easy way". Then, create the combined dummy item and just add the two individual dummies to that.
To show how much this automates, I've highlighted in green everything that was created in one step during the first "create the easy way". And if you add a new entry for either game to your wants, it will automatically be added to the right dummy item.
Also, if you're not sure how all of this works, maybe jump down to "How to turn these charts into wantlists", where I explain this exact scenario in detail.
Managing money wants with dummies (the easy way)
Before, we've created dummy items for different ranges of money. However, if you'd accept $20 for an item, I'd guess you'd also accept $30 or $40. This meant that we had to set several checkmarks for one game where it met with the different ranges. Wouldn't it be better to have money dummies that said "$20 or more"? But then we'd have to set checkmarks for every high money offer to be part of a bunch of different dummies. Chained dummies to the rescue! (Obviously)
The money dummies already allow an unlimited number of trades to go through them. So just say that every low money dummy also accepts the higher money dummies. Now everything can nicely cascade down.
You only want to trade one of two games away
Until now, we've only ever spoken about duplicate wants. But consider the following: You have both "Escape: The Curse of the Temple" and "Escape: Zombie City" in your collection and because you think they are too similar, you want to trade away one of them. You don't care which one, but you definitely want to keep the other. You can actually set up a "only one" guarantee (which is what duplicate protection is, really) just as easily for your haves as for your wants:
Obviously, this one doesn't require chaining so far. But because it's allowed, we can use this together with classic duplicate protection
Duplicate protection for more than one copy of a game
So far, we have always worked from the assumption that you only want to get one copy of a game (and, let's face it, in 99.9% of the cases that's true). But what if you actually want to get two copies, just no more than that? For example, maybe you want to get Star Realms and if you had two copies, you could play up to 4 players. I'll be honest, this requires a bit of setup, but it's possible, so I wanted to show it to you.
First, create two dummy items "Star Realms In" and "Star Realms Out", that are non-duplicate protected. One of those is the one that you add all the Star Realms offers to, the other dummy is the one you'll use to connect to your haves.
Then, create two (or however many copies you want to get) dummy items "Star Realms Limiter", that have duplicate protection.
Now just join them together as below and, tada, any of those Star Realms offers for any of those games, but no more than two in total.
You value many or all of your games the same
I didn't even think of that before, but there are of course traders who just want to trade as many games as possible, valuing all of their games the same or maybe just having two or three classes within which all trades are allowed. This is of course possible and actually pretty easy to set up, still retaining duplicate protection for individual games. So here's an example where all games are valued equally. You should of course be very sure that you actually are okay with all of the trades (even if you only get your worst want for your best have) before deciding on something like this.
How to turn these charts into wantlists
Someone asked me how these charts correlate to wantlists, and tbh, I should have added a bit more explanation on that from the beginning. If you already understand the charts, you can just skip this, if not, here's a detailed runthrough based on the first chained example "You only want one of two different games (the easy way)".
We start at Step 4, with two entries for Suburbia and three Castles of Mad King Ludwig already in your wants. From there, switch to "Duplicate Protection".
Over there, we'll begin by creating normal dummies for Suburbia and CoMKL the easy way:
You'll be redirected to the table view, but switch back to Duplicate Protection right away. Here we'll create another dummy item, this time manually, that contains the two previous dummies. To do so, give it an id and description, make sure that it isn't non-duplicate protected (i.e. the checkbox is not set) and then click Create.
Back in the table view, it's possible that the columns for your dummy items aren't displayed by default. If you don't see any columns with a green background, you'll need to click the green arrow at the top of the table to reveal them.
The first two dummies were created the easy way, so they're already connected to their respective game entries. However, we'll need to set the connection from those dummies to our "Suburbia or CoMKL" dummy ourself. Look for a row with one of the automatically created dummies, in this case, CoMKL. Set a checkmark at the intersection between that row and the column of your combined dummy. You will get a popup asking you confirm this, but you can just click OK on that. Do the same for the Suburbia dummy and we're almost set.
Finally, go to the row of our combined dummy and set the checkmarks which of your haves you'd like to trade for it. With that, we're done. And don't worry, it may seem lengthy in a detailed explanation, but once you've done it once or twice it's really quite easy.
So that's it. The very best guide on complex duplicate protection I could come up with. If anything's unclear, please ask. Also, is there anything else you can think of that's possible with chained dummy items?
I don't really have any plans for this, but I need somewhere to put my tutorials and maybe other stuff. Thus this.
- [+] Dice rolls