Checklist EUROAI (CEOAI) 2026 Contest Day 1 · Task 3
Clockwork Ellipses
From noisy position observations of synthetic planetary systems, recover each body's orbital parent and predict future positions.
The task
Each synthetic system has a fixed sun at (0, 0) (body 0, parent −1) and many bodies moving on ellipses relative to hidden parents (planets, moons, moons of moons). Only noisy coordinates at shared time snapshots are given, so the hierarchy is not obvious.
Subtask 1 (50 pts) asks for the parent of every body; Subtask 2 (50 pts) asks for (x, y) positions at future query times. For a true parent–child pair the relative motion is a single ellipse; after rebuilding the tree, orbits can be fitted relative to parents and propagated from the sun outwards.
Abridged by SOTA from the official materials. The official statement has the exact rules, and it wins wherever this summary differs.
At a glance
- You get
train_data.zipwithbodies.csv(system_id,body_id) andtrain.csv(system_id, time,body_id, x, y, noisy);test_data.csv(datapointID, subtaskID,system_id, time,body_id, answer blank).- You submit
submission.csvwith subtaskID, datapointID, answer: an integer parent ID for subtask 1 rows, and 'x,y' for subtask 2 rows.- Scoring
- Each subtask is scored out of 100 and halved. Subtask 1: accuracy of parent IDs; 5 if ≤ 20%, 100 at 100%, otherwise round(1.1875 × accuracy − 18.75). Subtask 2: RMSE over coordinates; 100 if ≤ 0.05, 5 if ≥ 10.0, otherwise round(100 − 41.285 × log10(RMSE / 0.05)).
- Rules
- Tested without a GPU and without internet access.
- Full test set must be answered in reasonable CPU time (the PDF says 4 minutes).
- Do not assume a fixed number of systems or bodies.
- Format
- Contest Day 1, 16 July 2026, 5 hours (10:30–15:30 local time; Nitro AI Judge 07:30–12:32 UTC), on-site at CREIC, Cluj-Napoca; three tasks, 100 points each.