About a month ago I spotted a new thread in the Geocoin Discussions thread on the Groundspeak Forums. Since I just started trading geocoins in January, my curiousity was piqued by the thread title: 3rd International Math Trade starting now!
Unlike a typical geocoin trade, when you negotiate one-on-one with the other party to the trade, the international math trade has 3 major phases, all coordinated by the math trade organizer.
FIRST, anyone who wants to participate creates their trade list. Oldest GeoKid helped me go through all our geocoins and we picked out 29 coins to participate in the math trade. We picked some coins that seemed to be sought after (i.e. they are on lots of seeking lists on geocoincollection.com), some coins that we thought would be appealing based on their appearance and some coins we just wanted to trade away. By the time everyone put their trade lists in, the 35 participants had placed a total of 709 coins into the trading pool, including an Avroair 2004 personal coin, a couple of Anthus laptops, a Loggerhead micro, some 2008 earth turtles, and many more we’d never seen before.
We then had a short period of time to "re-group", which is an opportunity to group 2 or more coins together as a single trade item. We decided to re-group a few of our coins, including putting our 3 da Vinci coins into one group, a Cached and Confused and a Cache or Charge into another, plus one other. We did this for strategic reasons, figuring, for example, the da Vinci set might actually have a chance of trading for something really good.
In the SECOND major phase, every participant builds their want list. For each item you’re trading (single coin or group from re-grouping phase), you build a prioritized list of coins that you’re willing to accept in exchange. For example, for our set of da Vinci coins we were willing to accept the Puzzle Cache 4-coin set, The Definitive GeoCoin 3-coin series, Loggerhead micro or an Anthus laptop. These lists must be submitted to the trade organizer in a prescribed format and there are certain coding instructions you can include to be sure you don’t get multiples of the same coin.
The THIRD major phase is where the "math" comes in. It seems some kind of linear programming application was written for the very first international math trade. The program optimizes all the want lists, to maximize the number of trades that can be done to satisfy the want lists. Once all the behind the scenes sorting out was completed, approx. 430 (61%) of the coins offered had traded. Our personal result was 7 coins that did not trade with the remainder (including all re-grouped coins) trading for some awesome coins: Loggerhead micro, Anthus laptop, Carousel Horse, Satellite Series 6, Phone A Friend, Triple Wisdom, Tantanka Pejula, and more.
We sorted, packaged and mailed our traded coins to 13 geocachers: 7 in the USA and 1 each in Australia, Austria, Canada, Germany, Sweden and the U.K. Total postage was $37.88, as all but one qualified as regular letter mail. And we’re looking forward to receiving 14 envelopes in the mail!! I wonder when the 4th International Math Trade will start?