3SUM by Ciro Santilli 40 Updated 2025-07-16
It is cool how even for such a "simple looking" problem, we were still unable to prove optimality as of 2020!
Jacquard machine by Ciro Santilli 40 Updated 2025-07-16
Video 1.
A Jacquard loom in action by NationalMuseumsScotland (2016)
Source. The lack of audio is unsettling!

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