To the uninitiated: The aim of regex golf is to create a regex (we're using ECMAScript), as short as possible, which matches all strings from one list while not matching any of the strings from the other. You can play the original version here which has easier puzzles.
For a short time, I'm offering small bitcoin rewards (order 20 mills) for what I consider novel and interesting solutions or cool custom problems. I'm also offering rewards for robust solutions (solutions that follow the implicit pattern) which are shorter than those I currently have.
Please don't post solutions on page 1 of this thread (I will delete them); hints and scores are ok. If you want to claim a reward before we reach page 2 then pm me or post the md5sum of your solution here and wait.
MD5sums of my current robust solutions:
| Subtraction: | 9b865d20497953a929057f11a35676bb |
| Typist: | d82bbea89153aef7b7c59ef1b8162f82 |
| Addition: | 3a1f41d29904651397f5d3be0af026df |
| Anyway: | ea913fef98314ee6655a174ff44e2d65 |
| Tic-tac-toe: | a5ed1fc5a8f6b18c2ae49c584c4d2ba2 |
| Modulus: | 3f4e8732b54806758181ac7db083d0cb |
| Matryoshka: | 3ed18e72eda9f52e5664f77a6381669d |
| Euclid: | 8d693dc7db1a222f4cc4a6bd2c0e9c75 |
| Latin squares: | 03d3c654c518a90ce2c1f8dcdc7ca13b |
| Dominoes: | 65d728d08c01d3678d95f12bc8b8a443 |
Many thanks to Davidebyzero for help with refining the problems and for some excellent solutions.