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Topic: 4 colors problem
Replies: 86   Last Post: Mar 13, 2014 4:36 PM

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stumblin' in

Posts: 58
Registered: 3/3/14
Re: 4 colors problem
Posted: Mar 5, 2014 5:56 PM
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"The 4-color theorem doesn't claim that every partial 4-coloring
of a planar graph can be completed to a full 4-coloring."

The unit pattern (in the previous post I called it the unit function, but meant "unit pattern") guarantees a full 4-coloring, so it's reliable.

"The claim of the theorem is that of _all_ possible valid
colorings, at least one of them uses at most 4 colors."

The unit pattern guarantees to use no more than 4 colors.

"Thus, to show that a given planar graph is a counterexample to
the 4-color theorem, it's not sufficient to produce a partial
4-coloring which can't be completed to a full coloring."

The unit pattern uses a partial 4-coloring which completes to a full coloring
for any-sized map and for any number of countries.

"You would have to show that _all_ possible valid colorings use
more than 4 colors, not just the one that you think makes sense."

What does this mean?

With a=blue, b=green, c=red, d=yellow,
Color the following map accordingly,

c d a b
a b c d
c d a b
a b c d
c d a b

which fulfills the promise of the 4 color theorem.
Now, let's say the second and third countries on the third row unites,
so they have to share the same color.
Now we have,

c d a b
a b c d
c d d b
a b c d
c d a b

How would you color this to fulfill the 4 color theorem using any coloring
order?






Date Subject Author
3/3/14
Read 4 colors problem
stumblin' in
3/3/14
Read Re: 4 colors problem
Brian Q. Hutchings
3/3/14
Read Re: 4 colors problem
stumblin' in
3/4/14
Read Re: 4 colors problem
g.resta@iit.cnr.it
3/3/14
Read Re: 4 colors problem
stumblin' in
3/4/14
Read Re: 4 colors problem
stumblin' in
3/4/14
Read Re: 4 colors problem
g.resta@iit.cnr.it
3/4/14
Read Re: 4 colors problem
stumblin' in
3/4/14
Read Re: 4 colors problem
stumblin' in
3/4/14
Read Re: 4 colors problem
stumblin' in
3/4/14
Read Re: 4 colors problem
stumblin' in
3/4/14
Read Re: 4 colors problem
stumblin' in
3/4/14
Read Re: 4 colors problem
g.resta@iit.cnr.it
3/4/14
Read Re: 4 colors problem
magidin@math.berkeley.edu
3/4/14
Read Re: 4 colors problem
stumblin' in
3/4/14
Read Re: 4 colors problem
Port563
3/4/14
Read Re: 4 colors problem
stumblin' in
3/4/14
Read Re: 4 colors problem
Brian Q. Hutchings
3/4/14
Read Re: 4 colors problem
stumblin' in
3/4/14
Read Re: 4 colors problem
stumblin' in
3/4/14
Read Re: 4 colors problem
stumblin' in
3/4/14
Read Re: 4 colors problem
stumblin' in
3/4/14
Read Re: 4 colors problem
Port563
3/4/14
Read Re: 4 colors problem
stumblin' in
3/4/14
Read Re: 4 colors problem
Brian Q. Hutchings
3/4/14
Read Re: 4 colors problem
stumblin' in
3/4/14
Read Re: 4 colors problem
stumblin' in
3/4/14
Read there should be a noncomputer proof of 4CT, I agree
Brian Q. Hutchings
3/4/14
Read Re: 4 colors problem
g.resta@iit.cnr.it
3/4/14
Read Re: 4 colors problem
stumblin' in
3/4/14
Read Re: 4 colors problem
Port563
3/4/14
Read Re: 4 colors problem
stumblin' in
3/5/14
Read Re: 4 colors problem
stumblin' in
3/5/14
Read Re: 4 colors problem
magidin@math.berkeley.edu
3/5/14
Read Re: 4 colors problem
stumblin' in
3/5/14
Read Re: 4 colors problem
magidin@math.berkeley.edu
3/5/14
Read Re: 4 colors problem
quasi
3/5/14
Read Re: 4 colors problem
stumblin' in
3/5/14
Read Re: 4 colors problem
magidin@math.berkeley.edu
3/5/14
Read Re: 4 colors problem
stumblin' in
3/5/14
Read Re: 4 colors problem
quasi
3/5/14
Read Re: 4 colors problem
magidin@math.berkeley.edu
3/5/14
Read also, what is the spatial analog
Brian Q. Hutchings
3/5/14
Read Re: 4 colors problem
stumblin' in
3/5/14
Read Re: 4 colors problem
magidin@math.berkeley.edu
3/5/14
Read Re: 4 colors problem
stumblin' in
3/5/14
Read Re: 4 colors problem
Brian Q. Hutchings
3/5/14
Read Re: 4 colors problem
Virgil
3/5/14
Read Re: 4 colors problem
stumblin' in
3/5/14
Read Re: 4 colors problem
stumblin' in
3/5/14
Read Re: 4 colors problem
stumblin' in
3/5/14
Read Re: 4 colors problem
stumblin' in
3/5/14
Read Re: 4 colors problem
stumblin' in
3/5/14
Read Re: 4 colors problem
stumblin' in
3/5/14
Read Re: 4 colors problem
Virgil
3/5/14
Read Re: 4 colors problem
stumblin' in
3/6/14
Read Re: 4 colors problem
Virgil
3/6/14
Read Re: 4 colors problem
Virgil
3/6/14
Read Re: 4 colors problem
Brian Q. Hutchings
3/6/14
Read Re: 4 colors problem
stumblin' in
3/6/14
Read Re: 4 colors problem
ross.finlayson@gmail.com
3/7/14
Read Re: 4 colors problem
Brian Q. Hutchings
3/7/14
Read Re: 4 colours problem
Robin Chapman
3/6/14
Read Re: 4 colors problem
stumblin' in
3/6/14
Read Re: 4 colors problem
stumblin' in
3/7/14
Read Re: 4 colors problem
magidin@math.berkeley.edu
3/7/14
Read Re: 4 colors problem
Peter Percival
3/7/14
Read Re: 4 colors problem
Peter Percival
3/6/14
Read Re: 4 colors problem
stumblin' in
3/7/14
Read Re: 4 colors problem
stumblin' in
3/7/14
Read Re: 4 colors problem
magidin@math.berkeley.edu
3/7/14
Read Re: 4 colors problem
Peter Percival
3/7/14
Read Re: 4 colors problem
Peter Percival
3/7/14
Read Re: 4 colors problem
stumblin' in
3/7/14
Read Re: 4 colors problem
stumblin' in
3/9/14
Read Re: 4 colors problem
stumblin' in
3/9/14
Read Re: 4 colors problem
Peter Percival
3/9/14
Read Re: 4 colors problem
stumblin' in
3/9/14
Read Re: 4 colors problem
magidin@math.berkeley.edu
3/9/14
Read Re: 4 colors problem
Brian Q. Hutchings
3/9/14
Read Re: 4 colors problem
stumblin' in
3/9/14
Read Re: 4 colors problem
stumblin' in
3/11/14
Read Re: 4 colors problem
stumblin' in
3/11/14
Read Re: 4 colors problem
Brian Q. Hutchings
3/13/14
Read Re: 4 colors problem
stumblin' in
3/13/14
Read Re: 4 colors problem
Brian Q. Hutchings
3/13/14
Read Re: 4 colors problem
stumblin' in

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