About Problempedia
An open library of problems that people post and solve together, problems they made up and problems they found, in physics first, and in mathematics and computer science too.
Most problem collections are written by one author and closed. Problempedia works the other way round. Anyone can post a problem, from a question that came up in their research to a twist on a textbook problem that made them think, and anyone can publish a solution under it. A problem never closes, so a second or third solution with a different method is as welcome as the first.
It grew out of Savchenko Solutions, where a community of students, teachers and researchers solved all the problems of one Russian textbook together, with drawings, simulations, literature reviews and a lot of jokes. Problempedia keeps that spirit and drops the limit of one book.
How it differs from a Q&A site
| Problempedia | A Q&A site | |
|---|---|---|
| What gets posted | A problem, made to be solved by others | A question the asker needs answered |
| After a good answer | Stays open for other methods and generalisations | One answer is accepted and the thread settles |
| A solution is | A credited write-up with figures, videos and references | An answer ranked by votes |
| Reading | Solutions stay folded until you choose to look | Answers are shown right away |
| Original work | Problems people made up carry an Original mark | No distinction |
Solutions
Write a solution the way you would explain it to a friend who is good at physics. State the setup, show the method, give the result and check it. Add a drawing, a plot, a short video of a simulation, or the papers where the idea comes from. Jokes are allowed.
There are no downvotes. Readers can like a solution, and the author of the problem can mark one as checked after reading it. Neither is a verdict, a solution can be good without either.
Marks on a problem
- Original
- The person who posted it made it up, or it came out of their own work.
- Archive
- A classic problem from a published source, added so there is something to solve from the first day. Its source is always named.
- Easy … Research level
- The author’s estimate at first. Once people solve it, the average of their ratings replaces it.
- Unsolved
- Nobody has posted a solution yet.
Authors can also say whether they tried an AI model on the problem and what happened. It is a note, not a filter. Problems are welcome either way, but a problem that only a person can crack is a good problem.
House rules
- Post problems you find interesting, not homework that is due tomorrow.
- If a problem is not yours, name its source. Copying a whole book is not welcome, a few favourite problems with credit are.
- Do not paste text generated by a model as your own solution. Use any tool you like, but the write-up is yours and you answer for it.
- Be kind in the discussion. Point at mistakes, not at people.
- Report spam and abuse with the Report link. Moderators hide it.
Languages
The site speaks English and Russian, switch with the EN and RU link at the top. Problems can be posted in either language and carry a mark when they are written in the other one.
Licence
Problems and solutions are published under CC BY-SA 4.0. You can reuse them anywhere with credit and the same licence. Archive problems keep the rights of their original sources and are quoted with attribution.
The archive account’s picture is a photograph by Archivo-FSP from Wikimedia Commons, under CC BY-SA 3.0.
