The following rules do not apply to teams from South Pacific
(Australia, New Zealand, etc.). World Finals teams will
be selected from the South Pacific Independent Regional Contest
independently of the other Asia Pacific regionals.
Basic rules of Asia Pacific regionals
A1. A team can participate in at most two regionals.
A2. If a regional is accompanied with preliminary contests, teams
from the hosting country of the regional must be qualified for the
regional through the corresponding preliminary contests.
A3. Regionals are expected to accept teams from other countries in
Asia Pacific. Each regional may set an upper-bound of the
number of foreign teams. The director of the regional may define
appropriate rules for selecting the foreign teams to be accepted.
A4. Regionals may accept teams from South Pacific as well as other
super-regions such as Asia East. These teams are never qualified
for the World Finals through Asia Pacific regionals.
A5. Teams from a country hosting a regional should not compete in two
regionals in other countries.
Selection rules for the World Finals (part 1)
B1. The winner team of each regional is directly qualified for the World
Finals. Here, “winner” is defined as the team with the highest rank
after excluding teams from other super-regions or South Pacific.
B2. If two or more teams from a single university are winners of different
regionals, only one of them is qualified for the World Finals.
The university should select one of them. Optionally, the university
can let the teams compete in the playoff to select one of them for the
World Finals. (These teams are invited to the playoff. See D1.)
B3. If one of the winner teams from a single university is to be selected
in the playoff (see B2), the team with the highest rank among them in
the playoff is qualified for the World Finals, regardless of the ranking
of teams from other universities in the playoff.
Site scores of regionals
C1. For each regional, its “site score”, say S, is defined as follows.
S = 0.56 * number of universities in the regional
+ 0.24 * number of teams in the regional
+ 0.14 * number of universities in the preliminary contests
+ 0.06 * number of teams in the preliminary contests
+ 0.30 * number of foreign teams in the regional
Here, only the teams solving at least one problem are counted.
Teams from South Pacific and other super-regions are counted (not
(Note) The above formula is copied from the World Finals team selection
rules in Asia Pacific since 2020.
Selection rules for the playoff
D1. The winner teams of regionals are invited to the playoff as open
participation teams. Their performance in the playoff does not
affect their qualification for the World Finals. There is an
exception if the teams are competing in the playoff due to the rules
B2 and B3.
(Note) From the winner universities, only the winner teams can compete
in the playoff. Other teams (second or lower in the regional
ranking) are not allowed to compete.
(Note) Winner teams are included in the playoff ranking, but are
removed in E1(1) below, not affecting the qualification of
teams from other universities.
D2. Apply the following procedures in this order, to the ranking of
each regional. (The regional is called X in the following.)
(1) Remove teams from South Pacific and other super-regions from the
(2) Remove teams not solving any problem from the ranking. Only
teams solving at least one problem are retained.
(3) Keep top 50% teams (rounded up) after the previous step, and remove
teams ranked lower than this. This means that lower 50% teams are
never qualified for the playoff.
(Note) The intent of step (3) is to never allow teams in the lower half
ranking of a regional to compete in the playoff. This step is
effective only in rare cases. For example, teams from under-
represented countries will not be qualified unless it gets a
rank in the top half. See D3(3).
(4) Remove the teams of winner universities from the ranking. Here,
a winner university is the university to which a winner team
(see B1) belongs. It may be the winner of the regional X, or
of another regional.
(5) Remove the fourth or lower ranked teams of each university from the
(Note) The maximum number of teams from a single university competing in
the playoff is 3. See D3(2).
(6) Recompute the team rank of each remaining team afresh. Let R be the
recomputed team rank of a team. Assign the following value to each
team in the ranking.
(R – 1) / S
S is the site score (defined in C1 above) of the regional X.
(Note) This definition and the following steps are based on Shieh-Ishihata
formula. It was the main part of the World Finals team selection
rules in Asia Pacific, before COVID-19.
D3. Merge the lists of teams from all regionals in Asia Pacific, and
apply the following procedures in this order to the resulting list.
(1) Sort the resulting list in ascending order of the value assigned above.
(2) Strike out the second instance of a single team, if any. Then,
strike out the fourth or later instances of teams of a single
university. This means that at most three teams are qualified from
a single university.
(Note) The fourth or lower teams are already removed in D2(5), but this
step is necessary.
(3) From each Asia Pacific country, select one team with the smallest
value. This team is qualified for the playoff.
(Note) This is a wild-card rule for under-represented countries.
At least one team is qualified from every country. However,
there is a condition. The team must be in the top half rank of
a regional. See D2(3).
(4) Let P be the number of teams for the playoff. Scan the list from
the team with the smallest value, and select teams one by one,
skipping those teams already selected in the step (3), unitl the
number of selected teams reach P. These teams are qualified for
D4. When an additional team should be selected, that is, when a qualified
team declines to participate in the playoff, reapply the rule D2
(and consequently D3) after removing that team from the ranking of
(Note) In the case of D4, site scores are not recomputed.
(Note) There will be no penalty to the teams declining to compete in the
Selection rules for the World Finals (part 2)
E1. World Finals teams are first selected according to B1 — B3 above.
Then, the teams with the highest playoff ranks are selected,
according to the following procedures.
(1) Strike out the teams with open participation status (winner teams
of regionals) in the ranking of the playoff.
(2) Strike out the second or lower ranked teams of a university in the
ranking of the playoff.
(3) Let N be the number of the World Finals slots allocated to Asia
Pacific. Let M be the number of teams qualified for the World Finals
in B1 — B3. Then, top N – M teams of the modified ranking are
qualified for the World Finals.
adopted July 17, 2023