But we can describe some of the ideas in words. Let’s say we have a regular expression which is supposed to match the strings (‘a’, ‘abab’, ‘aaaabb’, ‘bbc’).
The derivative of those strings with respect to
'a'is (’’, ‘bab’, ‘aaabb’) – you strip off theafrom every string.It turns out (which is not totally obvious to me, but I think if you go through all the cases it’s not too bad) that you can take the derivative of any regular expression in a pretty straightforward way – like if you have
(a+)|(b+), the derivative with respect toais(a+). These derivatives turn out to combine in nice ways which is I guess why they are called derivatives.
Steven Kalt · Apr 24, 2016
you can take the derivative of a regular expression?!
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But we can describe some of the ideas in words. Let’s say we have a regular expression which is supposed to match the strings (‘a’, ‘abab’, ‘aaaabb’, ‘bbc’). The derivative of those strings with respect to 'a' is (’’, ‘bab’, ‘aaabb’) – you strip off the a from every string. It turns out (which is not totally…
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