Regulations – Baltic Way 2020

The competition takes place virtually on November 14, 2020. Participation is by invitation only.
The participating teams consist of five contestants, a leader and a deputy leader. The contestants must be secondary school students or possible candidates for IMO 2021. They must not have formally enrolled at a university or any other equivalent post-secondary institution.
Each participating country nominates one or two members to the Problem Selection Committee (PSC). After the competition, PSC members fulfil the role of coordinators.
Competition will take place in each participating country separately starting at 8:30 UTC. If possible, students gather in one place and work together. If COVID-19 situation makes gathering in person too complicated or impossible, students are allowed to collaborate online.
The contest consists in solving 20 mathematical problems selected by the Problem Selection Committee. The time for the contest is 4 hours 30 minutes. Each team works together, and the contestants are free to discuss the works between them. Only writing and drawing materials are allowed during the contest; in particular, calculators, computers and telecommunication devices are not allowed for solving the problems. The solutions – at most one for each problem for each team – are to be written on the paper. The teams can use their own language.
If a team works online, computers and telecommunication devices can be used, but only as means of communication between students. When necessary, leaders of the respective country can invigilate such communication.
Leaders shall prepare and approve the translations of the problems to the languages used by the teams.
During the first 30 minutes of the contest, the teams may present written questions about the problems. Leaders together with PSC decide how the questions should be answered.
The solutions of single problems are marked by integers on a scale from 0 to 5 points. A preliminary marking is done by the leader and deputy leader of each team, and the final marking is done by the leader in collaboration with coordinators. If the leader and the coordinators cannot agree on the marking, the problem is considered by the Chair appointed by participating countries.
Ranking of teams will be decided by the sum of the marks of individual problems. In the case of a tie for the first, second and third prize, teams with a higher number of fives will be ranked above teams with a lower number of fives. If there is still a tie, the number of fours will decide the ranking. Then one counts the number of threes, and then the number of twos. If there is still a tie, the team having scored the most on the hard problems will be ranked above. This is determined in the following way: Let P(k) be a team’s score on problem k, and let T(k) be the total score of all the teams on problem k. Let Q be the sum of P(k) times T(k) taken over all 20 problems. Teams with a lower Q will be ranked above teams with a higher Q. If there is still a tie, leaders decide if and how the tie should be broken. In the case of a tie for the fourth place and lower, no action will be taken to resolve the tie.
The results (i.e., both partial and total scores, as well as rankings) are kept secret until the moment when they are officially announced at the closing ceremony of the competition.