Currently, the email address pow@mathsci.kaist.ac.kr is not working normally. Please submit your solutions to jioon.lee@kaist.edu instead. The due (for both POW 2025-13 and POW 2025-14) is postponed to Oct. 3 (Fri.) 23:59 pm.

Since there were no solutions submitted for POW 2025-13, we will postpone the due date of POW 2025-13 to Oct. 3 (Fri.) 3PM.

We remark that the problem is designed so that the answer with smallest number of punches earns +4, and the next four best answers earn +3 each. (In other words, you may earn some points even if your answer is not optimal.)

There was a condition missing in POW 2024-12, which is that every entry of \( A \) is \( 0 \) or \( 1 \). The condition in the problem is now corrected.

POW 2024 spring semester has ended. We apologize for many issues we had experienced this semester. Thank you for your participation, and see you in the fall semester.

It is found that there is a flaw in POW 2024-06; the inequality in the problem is not satisfied with the given g(t). Since it is too late to revise the problem again with a new deadline, we decide to cancel POW 2024-06. We apologize for the inconvenience.

Due to the change of the assumption in POW 2024-06, the due date for the submitting the solution is postponed to May 13 (Mon.) 3PM. (Originally, it was 3PM Friday.)

In POW 2024-06, there was a typo in the assumption. It is now corrected that the assumption holds for \( t \in [-1, 1] \). (Originally, it was for \( t \in \mathbb{R} \).)

POW 2024-05 is still open. (No correct solutions have been submitted.) Anyone who first submits a correct (full) solution will get the full credit.

In POW 2013-19, there was a typo in the assumption on \( a_1, \dots, a_{27} \). The inequality is now corrected to the equality.