CTK Exchange
Front Page
Movie shortcuts
Personal info
Awards
Reciprocal links
Terms of use
Privacy Policy

Interactive Activities

Cut The Knot!
MSET99 Talk
Games & Puzzles
Arithmetic/Algebra
Geometry
Probability
Eye Opener
Analog Gadgets
Inventor's Paradox
Did you know?...
Proofs
Math as Language
Things Impossible
My Logo
Math Poll
Other Math sit's
Guest book
News sit's

Recommend this site

Manifesto: what CTK is about Search CTK Buying a book is a commitment to learning Table of content Things you can find on CTK Chronology of updates Email to Cut The Knot Recommend this page

CTK Exchange

Subject: "4 colour mapping"     Previous Topic | Next Topic
Printer-friendly copy     Email this topic to a friend    
Conferences The CTK Exchange This and that Topic #431
Reading Topic #431
Starlight
guest
Aug-11-03, 10:31 AM (EST)
 
"4 colour mapping"
 
   The problem and answer are both posted on my site, https://www.angelfire.com/tv/dragonbllz/math.html , due to the fact that it is easier to express with a picture. Any thoughts, e-mail me at pronkyou2@yahoo.com.


  Alert | IP Printer-friendly page | Reply | Reply With Quote | Top

  Subject     Author     Message Date     ID  
4 colour mapping Starlight Aug-11-03 TOP
  RE: 4 colour mapping Vladimir Aug-12-03 1
     RE: 4 colour mapping mawcowboy Dec-04-03 2
  RE: 4 colour mapping Hypercoyote Nov-17-04 3
  RE: 4 colour mapping rewboss Nov-19-04 4
     RE: 4 colour mapping Starlight Jul-18-06 5
         RE: 4 colour mapping Silas Oct-25-06 6
             RE: 4 colour mapping Mark Huber Oct-27-06 7

Conferences | Forums | Topics | Previous Topic | Next Topic
Vladimir
Member since Jun-22-03
Aug-12-03, 09:12 AM (EST)
Click to EMail Vladimir Click to view user profileClick to add this user to your buddy list  
1. "RE: 4 colour mapping"
In response to message #0
 
   Four Color Theorem

https://www.ams.org/era/1996-02-01/S1079-6762-96-00003-0/S1079-6762-96-00003-0.pdf
Paper with a new proof by N. Robertson, D. P. Sanders, P. Seymour and R. Thomas (except the program code).

https://www.math.gatech.edu/~thomas/FC/fourcolor.html#Algorithm
Summary of a new proof by N. Robertson, D. P. Sanders, P. Seymour and R. Thomas.

https://www.mit.edu/~brun/pubs/fourcolors.pdf
Proves five color theorem.

https://www.mathpages.com/home/kmath266/kmath266.htm
Demonstrates the use of simpler and equivalent planar graphs rather than maps.

These are proofs or outlines of proofs (not that I have a chance with the paper). A few simple maps, a few confused lines about half of them, and a claim of the conclusion on your web page do not constitute a proof or anything close to it.


  Alert | IP Printer-friendly page | Reply | Reply With Quote | Top
mawcowboy
Member since Dec-4-03
Dec-04-03, 05:28 PM (EST)
Click to EMail mawcowboy Click to send private message to mawcowboy Click to view user profileClick to add this user to your buddy list  
2. "RE: 4 colour mapping"
In response to message #1
 
  
A formal proof guarantees its conclusion(s).

Currently, there does not exist a manipulation of algebraic symbols to obtain any formal proof of the Four Color Theorem.

Proofs of the Four Color problem are most directly related
with the history of Proof Without Words. ( search this site )

Four Color theorem 'proofs' are diagrams. If we see enough cases in which something is true and we never see a case in which it is false, we tend to conclude that it is always true. This type of reasoning by example is called inductive reasoning. Inductive reasoning is not considered proof within formal logic.

Deductive reasoning is the only one that guarantees its conclusions.


  Alert | IP Printer-friendly page | Reply | Reply With Quote | Top
Hypercoyote
guest
Nov-17-04, 00:37 AM (EST)
 
3. "RE: 4 colour mapping"
In response to message #0
 
   Does anyone know where to find the computer code they used to actually prove the 4 color theorem? I heard it was made publicly availible for refutation, but apparently not that publicly, because I cannot find it anywhere!!!


  Alert | IP Printer-friendly page | Reply | Reply With Quote | Top
rewboss
guest
Nov-19-04, 07:36 AM (EST)
 
4. "RE: 4 colour mapping"
In response to message #0
 
   What you've done, in effect, is to draw a few maps and then say, "Hey, I can't figure out how to draw a map that requires more than four colours". That's as far as the best mathematical brains got (at least before the advent of computers) -- nobody had been able to construct a map requiring more than four colours (and they tried a lot harder than you did), but that doesn't mean it's impossible.


  Alert | IP Printer-friendly page | Reply | Reply With Quote | Top
Starlight
guest
Jul-18-06, 08:47 AM (EST)
 
5. "RE: 4 colour mapping"
In response to message #4
 
   Oh, I have to love these. If you mathematically prove that the 5 colour theorem is true and useful in maps, then why not use it in a map? Using the same example in a theorem should make it'simple. This isn't to say it's impossible, it's to say there's no point to proving it. You're never going to have a living example of it. A proof without a visual is like asking a child to believe in god. They don't get it, but they'll do what their parent wants.

Please, do explain the proof. Preferably in colour.


  Alert | IP Printer-friendly page | Reply | Reply With Quote | Top
Silas
guest
Oct-25-06, 06:37 AM (EST)
 
6. "RE: 4 colour mapping"
In response to message #5
 
   You don't have to use the 5-color theorem in a map, because nobody has ever demonstrated a counter-example to the four-color theorem. In a sense the problem is not proving the four-color theorem - it is disproving it. Proving the four-color theorem just has mapmakers saying, "Phew!" and not having to worry about buying that fifth crayon. But if it were disproved, then the mathematical worlds opening up due to the vision of a kind of map nobody had ever seen or made use of before, could be almost limitless.

However, it'seems that, even though it is not an algebraic proof, there really will never be a counter-example and such dreams of finding new ways of mapping (or of new worlds to map) are come to nought.

In the absence of any real need for five colors, the hunt for a rigorous demonstrable proof is itself the hunt for new mathematical worlds, in which proof without words is not sufficient.


  Alert | IP Printer-friendly page | Reply | Reply With Quote | Top
Mark Huber
guest
Oct-27-06, 06:44 AM (EST)
 
7. "RE: 4 colour mapping"
In response to message #6
 
   The four-color theorem is more interesting from a socialogical rather than a mathematical point of view.

When the proof came out in the 70's, there was a lot of excitement, and many felt that computerized proofs of mathematics theorems were the wave of the future.

Simply put, that hasn't happened. Math journals are still pretty much the same as they were in the 70's, or even before the advent of the modern computer. What has changed is at the level of experimentation: a mathmatician nowadays will try to check what he or she believes to be true with as many computer generated examples as possible, before going for the full-blown mathematical proof.

And it turns out in the end not to be a very important problem. More interesting is the following: given a general graph (not necessarily planar), what is the minimum number of colors needed to color it? This problem is NP hard, and will get you a cool million from the Clay institute if you find a polynomial time algorithm that answers the question.


  Alert | IP Printer-friendly page | Reply | Reply With Quote | Top

Conferences | Forums | Topics | Previous Topic | Next Topic

You may be curious to have a look at the old CTK Exchange archive.
Please do not post there.

Copyright © 1996-2018 Alexander Bogomolny

Search:
Keywords:

Google
Web CTK