If you know regular expressions, you might find this to be geek fun. A friend of mine posted this, without a solution, but once I started working it, it seemed put together well enough it was likely solvable. Eventually I did solve it, but not before coding up a web interface for making it easier to interact with, which I recommend using if you are going to try this out. Or just print it out. Clic
![Regular Expression Crossword Puzzle](https://cdn-ak-scissors.b.st-hatena.com/image/square/4c001cb889f97088393907f5b2ec0a0f36c7515a/height=288;version=1;width=512/https%3A%2F%2Fgregable.com%2F2015%2F12%2Fi%2Fregexpuzzle.jpg)