specific regex to reduce

[brendan8229]

Look at this regex and see if our tool reduces it. It's a tiny example I was working on and found that the tool didn't reduce it.

[ab]{2}|c[abd]|[abc]d

The original has a lot of redundancy and I think should be reduced to [abc][abd].

[brendan8229]

I made a mistake above. Our tool doesn't have a way to get to a regex like [abc][abd] because it is not one node. If the original regex were

[ab][ab]|c[abd]|[abc]d

then we could get to [abc][abd] if we went in the right order or merges. But, if we merge [ab][ab] to [ab]{2}, then we would not get to [abc][abd].

[VladAndral]

I'm confused about how you got from the first regex to [abc][and]. Could you explain?

[brendan8229]

There are OR statements, so walk through all the possibilities. There are three little regexes connected by OR. The first allows for aa,ab,bb and ba. The second allows ca,cb and cd. The third allows ad,bd and cd. So the options for the first letter are [abc] and for the second is [abd].