Talk:Longest common subsequence problem/Archive 1

message: Unfortunately I haven't got the time to do so in a neat fashion right now. Anyway, here goes: suffix tree suffix array Bye! Shinobu 23:43, 4 Apr 2005 (UTC)
replies: text: Are you talking about an approximate solution? -- Nils Grimsmo 19:04, 7 August 2006 (UTC)
thread_title:  These wiki-links should be added somewhere 

message: I removed the C source, partly because it should be on Wikisource and not here, partly because if we should have a source on this we should use a better method, partly because we already have pseudocode source and partly because it was not formatted correctly. Of course I encourage anyone to put an optimized suffix array version on Wikisource and add a link here. Shinobu 12:39, 17 Apr 2005 (UTC)
replies: text: Wikisource isn't for source code - it's for old public domain texts (nothing to do with programming)! C code is often published on Wikipedia although pseudocode is generally preferable so I agree the C source should go. —EatMyShortz 02:04, 5 February 2006 (UTC)

text: Hmm.. I suppose algorithms count as "source text", just so long as the word "source" isn't confused - the "source" in "WikiSource" means that it's being taken from a primary or secondary source (see Primary source for definition), whereas the word "source" in "source code" means the original form of a program before being compiled, so it's a coincidence that the word is being used in two ways - Anyway here's their policy: What Wikisource includes#Source code —EatMyShortz 13:45, 19 February 2006 (UTC)
thread_title:  Removed C source 

message: This article should be called "longest common subsequence problem", not "longest-common subsequence problem". There is absolutely no reason to have a hyphen there.
:I guess you're right. But before you decide to move this article remember that there is still some research going on that perhaps may force a rename to "Longest common substring problem" anyway. Stay tuned, Shinobu 16:46, 26 Apr 2005 (UTC)
thread_title: Hyphen

message: Recently someone removed the algorithm, and then put it pack again, in such away as to remove the exernal links. I reverted the edit, but...
I think the algorithm reminds me very much of the LCSstring. I'll check if it is, and if so, I'll move it to the appropriate article. Shinobu 01:10, 27 August 2005 (UTC)
thread_title:  The algorithm 

message: This is a very poorly written page.  The C code is exactly the same as the recursion above it, only less comprehensible.  There is also no mention of the algorithms that are better than this one for large sequences.  --Zero 11:21, 9 November 2005 (UTC)
thread_title:  Cleanup 

message: From my understanding of the algorithm, the B table should have a lot less 0s. For instance anything to the right of a "left" cell should not say 0 - because at the very least it should look "left" to its left neighbour. Although the pictured B table doesn't relate to any specific example (perhaps it should), it seems invalid. Here's what I reckon a valid b-table might look like (based on the same b-table given, and I also made its corresponding C table):
C table:
:\begin{bmatrix} ! & 0 & 0 & 0 & 0 & 0\\  
 0 & 1 & 1 & 1 & 1 & 1 \\  
 0 & 1 & 1 & 2 & 2 & 2\\  
 0 & 1 & 1 & 2 & 3 & 3 \\  
 0 & 1 & 1 & 2 & 3 & 3 \\
\end{bmatrix}
B table:
:\begin{bmatrix} ! & 0 & 0 & 0 & 0 & 0\\  
 0 & UP-LEFT & LEFT & LEFT & LEFT & LEFT \\  
 0 & UP & UP & UP-LEFT & LEFT & LEFT\\  
 0 & UP & UP & UP & UP-LEFT & LEFT \\  
 0 & UP & UP & UP & UP & LEFT \\
\end{bmatrix}
It's quite a bit more confusing to look at but.. the other one seems wrong. I'll play more with the algorithm and see if I can confirm or deny this. Also what purpose does the '!' do? As far as I can tell you just stop when you hit a 0 in th b table. You don't necessarily finish at (0,0) anyway, that's only if the LCS starts at the beginning of the string! —EatMyShortz 02:15, 5 February 2006 (UTC)
thread_title:  Example: Incorrect B table? 

message: "An old method of searching for LCS was to employ a brute force policy: ..."  - says who?  Is there a known example where this "old algorithm" was used?  This page needs rewriting from scratch.  --Zerotalk 06:52, 7 May 2006 (UTC)
thread_title:  Very poor page