Beefy Boxes and Bandwidth Generously Provided by pair Networks
Clear questions and runnable code
get the best and fastest answer
 
PerlMonks  

comment on

( [id://3333]=superdoc: print w/replies, xml ) Need Help??
    "" "0" "00" "11" "000" "101" "0000" "1111" "1001" "1111" "00000" "10101"

I regret to inform you that 101 is not matched, though 110 and 011 are. (abell's solution is correct.)

I'm a bit gratified that people seem to be having a fairly difficult time with this (must be the (01*0)* group in the middle of the right-hand alternative; I think people tend to see the 01 as both bound by the *, rather than just the 1): means it's a useful example.

Oh, and the completeness proof for this regex matching multiples of three is fairly straightforward, once you have a minimal DFA for matching this regex. (In short: your minimal DFA has three states, each corresponding to a modulus of 3. 0 is the only accepting state, and you can prove by contradiction that all multiples of 3 end up in the 0 state.) Maybe I'll write it up when my profs stop assigning me papers. %-)

--
F o x t r o t U n i f o r m
Found a typo in this node? /msg me
The hell with paco, vote for Erudil!


In reply to Re(2): Regex refresher by FoxtrotUniform
in thread Regex refresher by FoxtrotUniform

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":



  • Are you posting in the right place? Check out Where do I post X? to know for sure.
  • Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
    <code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>
  • Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
  • Want more info? How to link or How to display code and escape characters are good places to start.
Log In?
Username:
Password:

What's my password?
Create A New User
Domain Nodelet?
Chatterbox?
and the web crawler heard nothing...

How do I use this?Last hourOther CB clients
Other Users?
Others rifling through the Monastery: (5)
As of 2024-03-29 00:28 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    No recent polls found