# Regarding a crossword

### Down

1. any of bcbbbccccbc ccbcbcccbcbcca ba ccca ca but none of a bcaa
2. any of aaaaaaaaac aaaaaaaaaaaa a2aaaaaa a2ac but none of 2aaaac a2aaaacc a22ac
3. any of 234cb 234b 23444444cb 234444444b but none of 24cb 24b 2cb 3cb 23cb 234ccb

### Across

1. either of abb abbb but none of abbbb ab aabb
2. either of ]abc ]abbbbc but none of ]ac ]bc ]ab abc ]]abc
3. either of abca a but none of aa aba cba abba bcca
• This is my first puzzle of this sort and I request critiques and ideas for improvement. – msh210 Jan 12 at 23:51
• Sounds like it belongs here, but not quite? :) – Avi Jan 12 at 23:59

I think I solved it

The strings of characters in the clues seem like they can be described by regular expressions.

  [   a   2
a b { 2 , 3 }
c   ?   4
( ] ) a b + c
+   +   c
( a b c ) ? a
?   ?   b
Down
1 [bc]+a? (at least one of b or c (or mixed), then optional a)
2 a2?a+c? (a, then optional 2, then at least one a, then optional c)
3 234+c?b (23, then at least one 4, optional c, then b)
Across
4 ab{2,3} (a, then exactly 2 or 3 b's)
5 (])ab+c (], then a, then at least one b, then c)
6 (abc)?a (optional abc, then a)

The cell where 3 and 6 meet could also be a * and satisfy the conditions.

I liked this puzzle, I've never seen anything like it. The only improvement I can see is if you made it have only one solution (maybe by adding more negative test cases).

• I fixed 5 across. Also I meant to say you could replace it with a * – Matthew Jensen Jan 13 at 0:51
• Excellent. 5 Across was actually meant to be []]ab+c — which supports your point that I should've worked harder at making this have a unique solution. – msh210 Jan 13 at 0:52
• Just for curiosity, what are you using to test your regex? Using Javascript []] doesn't match ], whereas (]) (or even ]) does match. – Matthew Jensen Jan 13 at 0:54
• Perl 5. []] matches just the character ] there. – msh210 Jan 13 at 0:55
• I'd hazard a guess that the title is also a clue: Re is a synonym for regarding and RE is the abbreviation for Regular Expression – postmortes Jan 13 at 11:14