3.9 Can this system be used for Online Rating?

A tournament is nothing more and nothing less than a set of many games played in one event. The rating system considers this by making several consistency checks over the input data. If, e.g. A plays against B , then B must play against A in the same round. There are about ten other checks of this type.

The resultant ratings do not change, if you split the tournament into many small tournaments. The situation of online-rating is an extreme case of this: Each tournament consists of one game only. Therefore this system can be used for online-rating too.

The bad thing is that there are some issues to be resolved:

• Due to the dynamic allocation and the numerics the calculation takes a lot of CPU-time. The current implementation starts from scratch after each tournament. It iterates through all the games (starting at 1994). A lot of time could be saved by caching intermediate results. This issue is on the to-do-list (with low priority).

• The algorithm, which is implemented in strict ISO-C++, is anything but simple. Because of its language, it is available on (almost) any 32-bit operating-system. Due to the lack of efficiency, there is no way to port it to scripting-languages like perl. And java seems to inefficient too. Therefore, to do it online, you must find a server to run trusted native code.

This is the simplest solution of the problem, that comes into my mind right now: On condition you have a POP3, a SMTP, a FTP, and a HTTP-server, the following procedure should work. The servers are provided by most ISP. The procedure is like this:

1. After finishing a game, the program sends an E-Mail with the result in a standard format to a predefined address (using SMTP).

2. A rating-computer, which may be offline most of the time, retrieves the mail (using POP3).

3. The rating-computer calculates the new ratings offline. There is no need to be online during this step.

4. The rating-computer transmits the results to the WEB-server (using FTP).

5. The player can access the updated rating (using HTTP).

The whole programming of the rating-computer can easily be done by a very simple shell-script on any UNIX-like system.

Another method is to use a simplified (and fast) calculation after each game. This can be done by a perl-script. And do the full iteration later.