Python's re module and genealogy problem
Thomas Rachel
nutznetz-0c1b6768-bfa9-48d5-a470-7603bd3aa915 at spamschutz.glglgl.de
Wed Jun 11 09:55:18 EDT 2014
Am 11.06.2014 14:23 schrieb BrJohan:
> Can it, for a pair of regular expressions be decided whether at least
> one string matching both of those regular expressions, can be constructed?
>
> If it is possible to make such a decision, then how? Anyone aware of an
> algorithm for this?
Just a feeling-based statement: I don't think that is easily possible.
Every RE can potentially match an infinite number of statements.
Just have a look at
re1 = re.compile('A43.*')
re2 = re.compile('.*[0-9][A-F]')
It can easily seen that the area these REs work on is different; they
are orthogonal.
So there is an infinite number of strings these REs match.
Thomas
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