In calculating the Ladder rankings, I’ve run in to a minor but significant glitch that will require a rules change to fix. See below for the gory details as to the whys and hows.

The resulting rules change is that (to be reasonably fair, and to avoid a major software rewrite) players who are absent or do not play any Ladder games for two consecutive club nights will be moved to the bottom of the Ladder, and will be taken off the Ladder after three such nights. This demotion in rank will happen after all the games for that night have been rated.

Now, on to the gory details…

The way the original rules treated absences is that when a player was absent, or didn’t play any Ladder games on a given club night, they would be demoted one rank.

For example, if there were four players on the Ladder, and players 2 and 3 were absent or did not play a Ladder game that night, then player who was originally ranked 2 would consequently fall to rank 3 and the player originally ranked 3 would fall to rank 4.

So far so good. But what happens to the player originally ranked 4 ? Well, with the system set up the way it is now, there are two solutions:

Solution A: The player originally ranked 4 moves up and assumes rank 2.

Solution B: The player originally ranked 4 gets moved down one rank, becoming ranked 5, and rank 2 remains empty.

Now, solution B does not seem very fair, because player 4 is effectively penalized for other players’ absences.

Solution A at first doesn’t seem so bad. But imagine the same thing happened on a Ladder with 10 players, where the top 9 players were absent. Then, implementing solution A, the absent players would all move down a rank, and player 10 would become ranked 1. That’s a huge, arguably unfair, increase in rank resulting from a bunch of players being absent for just one day. It becomes even more unfair if there were 11 players, and player 10 became ranked 1, while the 11th player (who’s ostensibly just a bit weaker than player 10) remains at the same rank.

This last problem could be mitigated by moving all the players below those that were absent above the absent players, but then the absent players would effectively be demoted more than one rank for their single absence, and the problem of the non-absent players instantly rising a great number of ranks simply because other players were absent would remain.

So, the only really fair solution would require changing the Ladder system and allowing more than one player to have the same rank. Thus, in the example of a four-player Ladder where players 2 and 3 were absent, the player originally ranked 2 would now be ranked 3, the player originally ranked 3 would now be ranked 4, and the player originally ranked 4 would remain where he was. This would result in two players being ranked 4, and rank 2 would be empty.

Unfortunately, the Ladder software I’ve written was designed for only player per rank. Allowing more than one person per rank would require a nearly complete rewrite, and I’m just not up to spending days on a rewrite right now.

So that’s why I’ve decided to go with the less than perfect solution described at the beginning of this post. This solution penalizes absences more strongly than I’d like, but it’s better than any of the other solutions I could implement at such short notice, and it’s also better than ignoring absences completely, which would result in players remaining permanently at their rank even if they’re no longer active, which isn’t fair to the other players who may want to rise to that rank. Imagine if player 1 was absent for 5 meetings and he was allowed to remain at the same rank. I think that would result in a lot of frustration for the rest of the players.

So, I think we’re going to have to go with this compromise solution… unless someone has a better suggestion.