Open sourced positional puzzles

I have worked with three very strong players to mine part of the Lichess games database to find positions that can be used as positional, rather than tactical, puzzles. The idea is that there are loads of resources for tactical puzzles, but not as many for positional puzzles, and that practice and repetition are key once you've understood the various concepts.

The positions are categorised by theme, and each have a difficulty rating.

They are open source, so feel free to do what you like with them.

You can find them in PGN and CSV formats here:

https://github.com/neilgd/chess-position-analysis-results

Thank you to following people for all their help:

* WIM/FM Liwia Jarocka
* WGM Michalina Rudzińska
* WGM Margarita Voyska
* Vlad Ghita for his work on exploring the data with machine learning in mind
* 'Fiddler' for his guidance