Python's re module and genealogy problem

[Simon Ward]

On 11 June 2014 13:23:14 BST, BrJohan <brjohan at gmail.com> wrote:
>For some genealogical purposes I consider using Python's re module.
>
>Rather many names can be spelled in a number of similar ways, and in 
>order to match names even if they are spelled differently, I will build
>
>regular expressions, each of which is supposed to match  a number of 
>similar names.

As has been mentioned, you probably want to look at fuzzy matching algorithms rather than aiming at regular expressions, although a quick search suggests there has been some work on fuzzy matching with regular expressions[1].

>Now, my problem: Is there a way to decide whether any two - or more -
>of 
>those regular expressions will match the same string?

If your regexes are truly regular expressions (see [2]*) then they represent regular languages[3], which are really sets. The intersection of these,  is another regular language. If you test the string against this it will also match both original languages.

(*this only mentions back references, but I think the look-ahead/behind assertions are also non-regular)

[1]: http://laurikari.net/tre/about/
[2]: https://en.wikipedia.org/wiki/Regular_expression#Patterns_for_non-regular_languages
[3]: https://en.wikipedia.org/wiki/Regular_language

Simon
-- 
Sent from Kaiten Mail. Please excuse my brevity.