The participants must solve a series of different types of chess problem in a set amount of time. Points are awarded for correct solutions in the least amount of time. The highest score at the end of the competition is proclaimed the winner.
Format
The Tournament consists of six rounds over two days, with three rounds each day according to the following table:
Team Championship – To qualify as an official team world championship, there must be at least seven teams from seven countries present. This section has grown from nine teams in 1977 to now averaging 20.
Individual – Likewise, for an official individual world championship to take place, 30 solvers from at least 10 countries must participate. This number too has grown from 18 in 1977 to well over 70 in the past six years (as of 2007).
Women and Juniors (up to 23 years old) – This event only requires 10 solvers from at least seven countries.
Rating
Formulas
We assume that the tournament has n solvers, with ratings (i = 1, ..., n) and in the tournament their scores are (i = 1, ..., n).
For players who didn't already have a rating, a preliminary rating is calculated. This rating is determined at the end of the first tournament in which the solver has participated. The formula that is used to calculate this rating is:
preliminary rating =
For players who already have a rating, the new rating is calculated as follows.
Rat = most recent rating of the solver
ExpSco =
TC = tournament coefficient, a number between 1 and 4; when the tournament is stronger, the TC is higher
ChangeRat =
NewRat = new rating =
These formulas are the defaults. If parameters fall outside a predetermined range, correction calculations are being carried out. These can be found in the reference.