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 Former security guard solves math puzzle
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the_ignored
SFN Addict

2562 Posts

Posted - 03/21/2008 :  03:31:19  Show Profile Send the_ignored a Private Message  Reply with Quote
The story can be found here, while the guy's solution can be found here.

What are any practical applications?

Well, apparently
Joel Friedman, a math professor at the University of British Columbia, said probably everyone in the field of symbolic dynamics had tried to solve the problem at some point, including himself. He said people in the related disciplines of graph theory, discrete math and theoretical computer science also tried.

"The solution to this problem has definitely generated excitement in the mathematical community," he said in an e-mail.

Margolis said the solution could have many applications.

"Say you've lost an e-mail and you want to get it back - it would be guaranteed," he said. "Let's say you are lost in a town you have never been in before and you have to get to a friend's house and there are no street signs - the directions will work no matter what."


I find that hard to swallow, but then I'm not friggen' genius.


>From: enuffenuff@fastmail.fm
(excerpt follows):
> I'm looking to teach these two bastards a lesson they'll never forget.
> Personal visit by mates of mine. No violence, just a wee little chat.
>
> **** has also committed more crimes than you can count with his
> incitement of hatred against a religion. That law came in about 2007
> much to ****'s ignorance. That is fact and his writing will become well
> know as well as him becoming a publicly known icon of hatred.
>
> Good luck with that fuckwit. And Reynold, fucking run, and don't stop.
> Disappear would be best as it was you who dared to attack me on my
> illness knowing nothing of the cause. You disgust me and you are top of
> the list boy. Again, no violence. Just regular reminders of who's there
> and visits to see you are behaving. Nothing scary in reality. But I'd
> still disappear if I was you.

What brought that on? this. Original posting here.

Another example of this guy's lunacy here.

Cuneiformist
The Imperfectionist

USA
4955 Posts

Posted - 03/21/2008 :  06:16:18   [Permalink]  Show Profile Send Cuneiformist a Private Message  Reply with Quote
Was his name Matt Damon?
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recurve boy
Skeptic Friend

Australia
53 Posts

Posted - 03/21/2008 :  09:23:38   [Permalink]  Show Profile Send recurve boy a Private Message  Reply with Quote
http://en.wikipedia.org/wiki/Road_Coloring_Conjecture

So this still means that we need signs. But this way we don't need to pay attention to the names. All we need to do is colour the roads. Now your friend doesn't have to give you his address. He just gives you a list of instructions. And this will work regardless of your starting point. And maybe his house number.

This is very useful. Imagine you are on vacation in a city. You want to explore. You never need to remember where you are. You just remember the code the hotel gave you. And every day you can take a new blue road and not get lost.
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filthy
SFN Die Hard

USA
14408 Posts

Posted - 03/21/2008 :  10:09:24   [Permalink]  Show Profile Send filthy a Private Message  Reply with Quote
The truckers would appreciate that!




"What luck for rulers that men do not think." -- Adolf Hitler (1889 - 1945)

"If only we could impeach on the basis of criminal stupidity, 90% of the Rethuglicans and half of the Democrats would be thrown out of office." ~~ P.Z. Myres


"The default position of human nature is to punch the other guy in the face and take his stuff." ~~ Dude

Brother Boot Knife of Warm Humanitarianism,

and Crypto-Communist!

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Ricky
SFN Die Hard

USA
4907 Posts

Posted - 03/21/2008 :  10:14:23   [Permalink]  Show Profile  Send Ricky an AOL message Send Ricky a Private Message  Reply with Quote
That only works if the graph is aperiodic. That is a fairly strong condition which isn't hard to explain, but has no parrallel in "reality". What I mean is that a directed edge is like a one way street, if you take a bridge out things become disconnected, and a forest is a collection of trees. But there is non-mathematical way to describe an aperiodic graph.

If anyone is curious, the wikipedia article is pertty good.

The condition of the graph being strongly connected will rule out other cities as well, but there are enough two way streets that this normally doesn't happen.

This does have implications for the developement of local networks, but I believe that the condition of the graph being aperiodic once again rules out any applications of this. But I am an amature when it comes to network design and theory. Perhaps it has use in distributed computing, but again, it seems small.

Why continue? Because we must. Because we have the call. Because it is nobler to fight for rationality without winning than to give up in the face of continued defeats. Because whatever true progress humanity makes is through the rationality of the occasional individual and because any one individual we may win for the cause may do more for humanity than a hundred thousand who hug their superstitions to their breast.
- Isaac Asimov
Edited by - Ricky on 03/21/2008 10:17:44
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Dr. Mabuse
Septic Fiend

Sweden
9688 Posts

Posted - 03/21/2008 :  12:21:44   [Permalink]  Show Profile  Send Dr. Mabuse an ICQ Message Send Dr. Mabuse a Private Message  Reply with Quote
Originally posted by Ricky
Perhaps it has use in distributed computing, but again, it seems small.
Then perhaps Siberia will have some input. She did school work on distributed computing.

I really hope she's ok. I haven't heard from her in what feels like ages.


Dr. Mabuse - "When the going gets tough, the tough get Duct-tape..."
Dr. Mabuse whisper.mp3

"Equivocation is not just a job, for a creationist it's a way of life..." Dr. Mabuse

Support American Troops in Iraq:
Send them unarmed civilians for target practice..
Collateralmurder.
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filthy
SFN Die Hard

USA
14408 Posts

Posted - 03/21/2008 :  12:30:12   [Permalink]  Show Profile Send filthy a Private Message  Reply with Quote
I too, have been wondering. We also seem to be missing Beskeptigal.

As for the math, I don't understand a bit of it. But then I have trouble counting change and due to this, I consider debit cards a blessing -- don't have to deal with change.




"What luck for rulers that men do not think." -- Adolf Hitler (1889 - 1945)

"If only we could impeach on the basis of criminal stupidity, 90% of the Rethuglicans and half of the Democrats would be thrown out of office." ~~ P.Z. Myres


"The default position of human nature is to punch the other guy in the face and take his stuff." ~~ Dude

Brother Boot Knife of Warm Humanitarianism,

and Crypto-Communist!

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Ricky
SFN Die Hard

USA
4907 Posts

Posted - 03/21/2008 :  15:19:28   [Permalink]  Show Profile  Send Ricky an AOL message Send Ricky a Private Message  Reply with Quote
My previous statement was entirely incorrect.


The condition of the graph being strongly connected will rule out other cities as well, but there are enough two way streets that this normally doesn't happen.


This will never happen. Strongly connected means you can get from any vertex to any other vertex. In other words, there is always a way to get to where you want to go. It's hard to imagine a city where it's not possible for you to get from one place to another.

Unless you're Steven Wright:

I bought a house, on a one-way dead-end road; I don't know how I got there, but I can't leave.

Why continue? Because we must. Because we have the call. Because it is nobler to fight for rationality without winning than to give up in the face of continued defeats. Because whatever true progress humanity makes is through the rationality of the occasional individual and because any one individual we may win for the cause may do more for humanity than a hundred thousand who hug their superstitions to their breast.
- Isaac Asimov
Edited by - Ricky on 03/21/2008 15:21:33
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recurve boy
Skeptic Friend

Australia
53 Posts

Posted - 03/21/2008 :  16:14:54   [Permalink]  Show Profile Send recurve boy a Private Message  Reply with Quote
Originally posted by Ricky
The condition of the graph being strongly connected will rule out other cities as well, but there are enough two way streets that this normally doesn't happen.


I don't see a reason why we cannot artificially force this condition just for the purposes of creating a coloured map.

E.g. take those tourist maps. Those are often incomplete and only contain certain major roads or attractions. We can lay our coloured map on top of that. And now we can explore without having to work out the city.
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Ricky
SFN Die Hard

USA
4907 Posts

Posted - 03/21/2008 :  17:45:01   [Permalink]  Show Profile  Send Ricky an AOL message Send Ricky a Private Message  Reply with Quote
recurve, I posted a correction to my previous statement. And let me correct another. The condition of an aperiodic graph is not a strict as I thought it to be, especially when looking at real world conditions. A two way road is an example of a 2-cycle, and all network connections that I am aware of are also 2-cycles. Thus, so long as any (2k+1)-cycle exists as well (where k is an integer), the graph will be aperiodic.

However, there is still a requirement that the graph have the same out-degree for every vertex k. This seems to be rather strict, but I'd like to reflect on it for a while before coming to a conclusion.

Why continue? Because we must. Because we have the call. Because it is nobler to fight for rationality without winning than to give up in the face of continued defeats. Because whatever true progress humanity makes is through the rationality of the occasional individual and because any one individual we may win for the cause may do more for humanity than a hundred thousand who hug their superstitions to their breast.
- Isaac Asimov
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Chippewa
SFN Regular

USA
1496 Posts

Posted - 03/21/2008 :  18:51:00   [Permalink]  Show Profile  Visit Chippewa's Homepage Send Chippewa a Private Message  Reply with Quote
I wonder if Mr. Trahtman will try the Sphere-Packing Problem next.

Diversity, independence, innovation and imagination are progressive concepts ultimately alien to the conservative mind.

"TAX AND SPEND" IS GOOD! (TAX: Wealthy corporations who won't go poor even after taxes. SPEND: On public works programs, education, the environment, improvements.)
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HalfMooner
Dingaling

Philippines
15831 Posts

Posted - 03/21/2008 :  20:33:00   [Permalink]  Show Profile Send HalfMooner a Private Message  Reply with Quote
Does this mean lots of new jobs for street painters?


Biology is just physics that has begun to smell bad.” —HalfMooner
Here's a link to Moonscape News, and one to its Archive.
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