Regex for bit strings with at least two zeros but no consecutive zeros
The shortest regex I came up with is: 1*01+0(1+0?)*


Start with arbitrary amount of 1s (1*)
Exactly one 0 (0)
One or more 1s (1+)
Another 0: (0)
Arbitrarily often ((...)*):


One or more 1s (1+)
At most one 0 (0?)