Re: [PR] [DRAFT] Case-insensitive matching over union of strings [lucene]

[via GitHub]

dweiss commented on PR #14350:
URL: https://github.com/apache/lucene/pull/14350#issuecomment-2720601955

   I think this will work just fine in most cases and is a rather inexpensive 
way to implement this case-insensitive matching, but this comes at the cost of 
the output automaton that may not be minimal. Consider this example:
   ```
       List<BytesRef> terms = new ArrayList<>(List.of(
               newBytesRef("abc"),
               newBytesRef("aBC")));
       Collections.sort(terms);
       Automaton a = build(terms, false, false);
   ```
   which produces:
   
![image](https://github.com/user-attachments/assets/5d89a382-0fe9-4b42-bdcc-a67cb2b90ef5)
   
   However, when you naively expand just the transitions for each letter 
variant, you get this:
   
![image](https://github.com/user-attachments/assets/2c55bbc5-1c16-43c9-b148-2effbd6b1efb)
   which clearly isn't minimal (and doesn't pass checkMinimized).
   
   I think the absolutely worst case is for the automaton to double the number 
of transitions - the number of states remains the same. So it's not like it's 
going to expand uncontrollably... But it's no longer minimal. Perhaps this is 
acceptable, given the constrained worst case?


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