Beefy Boxes and Bandwidth Generously Provided by pair Networks
Don't ask to ask, just ask

Re: Perl regular expressions vs. RL, CFL, CSL

by JadeNB (Chaplain)
on Dec 14, 2009 at 17:08 UTC ( #812749=note: print w/replies, xml ) Need Help??

in reply to Perl regular expressions vs. RL, CFL, CSL
in thread A few random questions from Learning Perl 3

NP-completeness is a property of an algorithm. It implies that no algorithm is known to solve the problem in polynomial time.
This means that if you increase the length of the input for the problem, the execution time will increase exponentially. (Of course there are input cases which are polynomial, but many of interest are not). Essentially, it means that brute force is the only known method to tackle the problem exactly.

I think that this may be a little misleading. Right now (as 6 years ago), NP-completeness of a problem means that no polynomial-time algorithm is known, but that statement may eventually become false *. Maybe it's better to say “Computer scientists believe that, if a problem is NP-complete, then there is no polynomial-time algorithm to solve it”?

Also, I'm not sure that it's fair to say that NP-completeness of a problem means that the time-complexity of the problem grows exponentially in the input. Again, we think that NP-completeness correlates with exponential time-complexity, but that could change *. For that matter, can't NP-complete problems have super-exponential complexity (like 2^(n^2))—or are you using ‘exponential’ in the generic sense of ‘faster-growing than polynomial’?

* Although we all know that it won't really. :-)

Log In?

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://812749]
[LanX]: A Team or McG ?
[Your Mother]: A-Team.
[LanX]: never liked it, but a friend of my mother was a big "fan" of Mr T xD
[LanX]: (talking about minority chicks)
[LanX]: Hollywood is built on stereotypes which sell, this includes stereotypes about English, French, russians and ... Americans
[Your Mother]: I think to some degree, maybe a large one, the stereotypes are purely products OF Hollywood and not what would sell best.
[LanX]: well those products which sold best are replicated
[Your Mother]: They get almost everything wrong on every level. I think they create and restrict the market and fundamentally misunderstand audiences.
[Your Mother]: Consider how long, for example, superhero movies were kept at bay because they weren't commercially viable. They always were, just Hollywood couldn't see it or understand how to make one because there is no management talent in the town.
[LanX]: Erich von Strohheim built his career on beeing the most hated guy (The man you love to hate)

How do I use this? | Other CB clients
Other Users?
Others lurking in the Monastery: (9)
As of 2018-03-19 14:54 GMT
Find Nodes?
    Voting Booth?
    When I think of a mole I think of:

    Results (240 votes). Check out past polls.