Talk:Divide-and-conquer algorithm

message: Inexplicably, this was included in the "See Also" section of this page, though it has not even a metaphorical relationship to these algorithms. I removed it.  —Preceding unsigned comment added by Ailun (talk • contribs) 06:10, 6 April 2010 (UTC)
thread_title:  Deleted reference to "Divide and rule (politics and sociology)"

message: The article had a section on the "Decrease and Conquer" (D-C) algorithms, defined as Divide and Conquer (D+C) algorithms where each call generates at most one recursive call (i.e., where the problem gets "divided" into at most one sub-problem).  I removed that section, since that approach seems rather pointless.  D-C algorithms are much easier to implement and understand using either iteration or simple recursion.  Besides, most of the discussion about D+C algorithms is irrelevant for D-C algorithms.  So, discussing D-C algorithms in the D+C article is like having a section in the matrix multiplication page that tells how one can multiply two real numbers by turning them into 1x1 matrices. The example algorithms that were given (finding the largest of N numbers) just prove the point: when the D-C paradigm can be applied at all, it produces nedlessly complex and inefficient code. All the best, --Jorge Stolfi (talk) 23:28, 24 October 2008 (UTC)
thread_title:  Deleted the "Decrease and Conquer" section 

message: The article was recently edited to extend the name "divide end conquer" so as to include some single-branch recursive algorithms, like binary search and Euclid's gcd (the "decrease and conquer" of some authors).  Apparently this broader definition f D+C has been adopted by some textbooks, like Cormen's.  However, if Euclid qualifies as D+C, then what algorithm does NOT qualify?  Every looping algorithm can be trivially rewritten as a single loop (per Bohm&Jacopini) and then as a sngle-branch recursive procedure.  So, where would we draw the line? --Jorge Stolfi (talk) 07:19, 11 March 2009 (UTC)
thread_title: Decrease and conquer, undead

message: The article had a short section on a supposed "Divide and marriage before conquest" paradigm, in which "solutions to the subproblems generated by the recursion are combined to obtain a solution to the original problem", with mergesort cited as one example.  Reference given: .  But that is precisely the definition of the D&C paradigm, isn't it? --Jorge Stolfi (talk) 23:40, 24 October 2008 (UTC)
thread_title:  Deleted "Divide and Marriage before Conquest" section 

message: I don't know the answer to this question. Anybody knows? Alexander the Great didn't assume a fast computational algorithm.
Also von Neumann. But the description of the D&C, described on this webpage above, unites very dofferent algorithms from very different regions of science and life, fast and not fast. Who did such a unification?  —Preceding unsigned comment added by Algoritmist (talk • contribs) 13:26, 6 December 2008 (UTC)
replies: text: The description on this page is totally standard in computer science; please stop this pointless and misguided campaign. —Steven G. Johnson (talk) 15:49, 6 December 2008 (UTC)
thread_title:  Who was the author of the name "Divide and Conquer" for certain kind of computational algorithms ? 

message: The problem is that here in "Divide and Conquer" topic different algorithms and approaches were mixed, what is absolutely incorrect and bad for readers who are not specialists in the considered subjects. 
What relation "Merge Sort" has to fast computational algorithms? Can you increase the efficiency of calculation of, say, sinus of x, applying the von Neumann idea? No. You can not. So it is a great difference between the Karatsuba idea and the von Neumann idea. Using the Karatsuba you obtain a tool for calculation of a great number of functions, intagrals and series much more effectively.
Using von Neumann --- you obtain almoust nothing. How it is possible not only to compare these two approaches, but even to "put them in one box"? 
Karatsuba didn't use the "divide and Conquer" paradigma to invent his method, he just invented such a general method  that permit to increase the efficiency of the computer work. After the Karatsuba invention the name "Divide and Conquer" was introduced, not before. To equal such different by importance results as the Karatsuba method and von Neumann Sorting means to diminish the advantage of the Karatsuba result. 
Knuth in his "Art of Computer Programming" is writing that the Karatsuba idea was not known till 1960 (4000 years of calculations and multiplications). Seems, Donald Knuth is not agree with the authors of D&C paradigma, believing that the Karatsuba idea is the same that von Neumann idea.  —Preceding unsigned comment added by 83.149.209.253 (talk) 15:09, 31 March 2010 (UTC)
replies: text: The description on this page is totally standard in computer science; please stop this pointless and misguided campaign. —Steven G. Johnson (talk) 15:49, 6 December 2008 (UTC)
thread_title:  This subject is incorrect 

message: The commons picture :File:Array maximum - divide et impera.png nicely illustrates all aspects of a d+c algorithm. However, I hesitate to show it in the article since the problem it solves (finding the maximum value in an array) can better be solved by linear search. Maybe somebody can obtain a similar image, but about a d+c algorithm that is optimal? - Jochen Burghardt (talk) 06:05, 12 April 2017 (UTC)
thread_title:  Picture 

message: Hi,
The recursive Towers of Hanoi algorithm which solves the problem by moving n-1 disks to the intermediate peg, the nth disk to the final page, and the n-1 disks from the intermediate peg is a great example of a recursive solution to a puzzling problem.  However it is not a divide and conquer algorithm.  In divide and conquer algorithms a problem of size n is typically split into m more or less equally sized subproblems (where m is usually 2, but sometimes more), then the subproblems are solved recursively, and their solutions are then combined to get a solution to the original problem.  This does not take place in the Towers of Hanoi algorithm.  In this algorithm, there are two recursive function calls, but their recursions are on subproblems of size n-1, and not on subproblems of size n/m.   This algorithm is better classified as a "reduce by 1" algorithm, and not as a "divide and conquer" algorithm.
Saquigley (talk) 07:32, 11 March 2018 (UTC)
thread_title:  Towers of Hanoi is not a divide and conquer algorithm 

message: At the picture illustrating MergeSort algorithm, I assume it would be better to skip some levels with one-element fragment "10" (only one such level should remain, not three equal ones), with repainting corresponding arrows not one level down, but either two arrows two layers down each, or maybe one arrow one layer down, one arrow three layers down.
Reason: one-element fragment "10" IS NOT divided into parts, there are NO recursive calls for it.
Draft visual presentation of the proposition is https://docs.google.com/drawings/d/1vO5Zg2Q6KI8ACnFCbfs4h4lwC9_foV2PJlu5ZgX0NXc IlyaCk (talk) 07:37, 9 December 2023 (UTC)
thread_title:  Picture: remove intermediate levels for "10"