Slashdot Mirror

Related links for this article:
DTN Research Group: http://www.dtnrg.org/wiki
lots of docs: http://www.dtnrg.org/wiki/Docs
overview presentation: http://jeroen.massar.ch/presentations/files/CCC2007-DTN-Upgrading-Martian-Carrier-Pigeons.ppt

The book: http://www.amazon.com/dp/1596930632
Wikipedia: http://en.wikipedia.org/wiki/Delay-tolerant_networking

Source code: http://dtn.dsg.cs.tcd.ie/sft/ltplib/

Oh and yes, theoretically this extends the Internet in the same way that various other protocols do, eg 6lowpan etc.
And yes, as it is store-and-forward it looks an awful lot like SMTP.

Enjoy ;)

Arbitrary standard? HTML 4 is an ISO/IEC standard: http://www.cs.tcd.ie/misc/15445/15445.html (or: http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=27688 )

Interesting theory.

Not motion compensation, but
http://www.cse.cuhk.edu.hk/~ttwong/demo/dwtgpu/dwtgpu.html

Brook GPU speculates about possibility when released in '04 too

nVidia does it in '04 with the 6xxx series, but it was a dedicated chip, which is different.

Not smart enough to know what it means, but this, published in '04
http://www.mee.tcd.ie/~sigmedia/pmwiki/uploads/Main.Publications/kelly04a.pdf
is titled "Graphics Hardware for Gradient Based Motion Estimation"

and this (from '03) is titled General Purpose Graphics Hardware for Accelerating Motion Estimation
http://www.mee.tcd.ie/~sigmedia/Publications?action=upload&upname=kelly.pdf

source:
http://www.mee.tcd.ie/~sigmedia/Publications

Interesting theory.

Not motion compensation, but
http://www.cse.cuhk.edu.hk/~ttwong/demo/dwtgpu/dwtgpu.html

Brook GPU speculates about possibility when released in '04 too

nVidia does it in '04 with the 6xxx series, but it was a dedicated chip, which is different.

Not smart enough to know what it means, but this, published in '04
http://www.mee.tcd.ie/~sigmedia/pmwiki/uploads/Main.Publications/kelly04a.pdf
is titled "Graphics Hardware for Gradient Based Motion Estimation"

and this (from '03) is titled General Purpose Graphics Hardware for Accelerating Motion Estimation
http://www.mee.tcd.ie/~sigmedia/Publications?action=upload&upname=kelly.pdf

source:
http://www.mee.tcd.ie/~sigmedia/Publications

Interesting theory.

Not motion compensation, but
http://www.cse.cuhk.edu.hk/~ttwong/demo/dwtgpu/dwtgpu.html

Brook GPU speculates about possibility when released in '04 too

nVidia does it in '04 with the 6xxx series, but it was a dedicated chip, which is different.

Not smart enough to know what it means, but this, published in '04
http://www.mee.tcd.ie/~sigmedia/pmwiki/uploads/Main.Publications/kelly04a.pdf
is titled "Graphics Hardware for Gradient Based Motion Estimation"

and this (from '03) is titled General Purpose Graphics Hardware for Accelerating Motion Estimation
http://www.mee.tcd.ie/~sigmedia/Publications?action=upload&upname=kelly.pdf

source:
http://www.mee.tcd.ie/~sigmedia/Publications

TelMex controls 92% of the landline phones in the country and his affiliate cell phone business, Telcel, accounts for 73% of the mobile business. The wealth and power derived from these companies has allowed Slim to expand his business empire across a wide swathe of industries."

Monopolies are obviously highly profitable for a few. Besides the economic cost to the those funding el imperio de Carlo Slim Helu, have the Mexicans actually weighed up the social costs of supporting it?. ...Or is it that the Mexicans do not have a government that represents their best interests...?

Half the fun of wikipedia is looking up something, then wasting a couple hours wandering through topics till you get someplace you might not have gone otherwise.

.. which lead to a very cool project, posted on /. a few months ago:
The slashdot article: Six Degrees of Wikipedia
The project itself: Six Degrees of Wikipedia

I had some fun messing around with this... very cool. If you're too lazy to click the links above, essentially it lets you calculate the lowest number of links between two Wikipedia articles! Awesome.

Did you know you could get from the article on Hitler to that on Diarrhea with only 2 mouse clicks?

You do realize that there's only one degree of separation between the two anyway, right?

on a great new internet toy.

Incidentally, the shortest path from Mortification to Gratification is through Sufism.
http://www.netsoc.tcd.ie/~mu/cgi-bin/shortpath.cgi?from=Mortification&to=Gratification

Shortest path from salami attack to anal rape
Salami attack
Fraud
Crime
Rape
3 clicks needed

Getting from Slashdot to The Center of the Universe is just that easy! Pretty interesting: we use Apple and Islam to get there.

There is no connection between Chuck Norris and Awesome (there is no whoopass article)
http://www.netsoc.tcd.ie/~mu/cgi-bin/shortpath.cgi?from=Chuck+Norris&to=Awesome

Here's a separation of five for two random articles, for example:

Shortest path from JÃlabÃkaflÃÃ to John Norreys (Keeper of the Wardrobe)

JÃlabÃkaflÃÃ (sorry, Slashdot's inability to cope with Latin1 characters messes this up, but you can check the link to see what it really is)
Christmas
January 5
Richard, 1st Earl of Cornwall
High Sheriff of Berkshire
John Norreys (Keeper of the Wardrobe)

5 clicks needed

And Goatse is only 2 clicks away, via April 30th here

found it!

http://www.netsoc.tcd.ie/~mu/cgi-bin/shortpath.cgi?from=Tacoma+Narrows+Bridge&to=Wet+T-shirt+contest

4 clicks needed B)

yeah, but: http://www.netsoc.tcd.ie/~mu/cgi-bin/shortpath.cgi?from=Tacoma_Narrows_Bridge&to=Wet_T-shirt_contest

unless I'm doing it wrong...?

hell or not? http://www.netsoc.tcd.ie/~mu/cgi-bin/shortpath.cgi?from=Slashdot&to=Double+penetration+dildo

Slashdot
Goatse.cx
Dildo
Double penetration dildo

If you thought that was funny, you should see the path from Sex to Satan... http://www.netsoc.tcd.ie/~mu/cgi-bin/shortpath.cgi?from=sex&to=satan This couldn't be more perfect.

Every one remember,

Its only 1 click form Heaven to hell

http://www.netsoc.tcd.ie/~mu/cgi-bin/shortpath.cgi?from=Heaven&to=Hell

Who knew it was this easy!

Shortest path from hillary clinton to antichrist

Hillary Rodham Clinton
Jerry Falwell
Antichrist
2 clicks needed

Shortest path from Kevin Bacon to drug overdose:

Kevin Bacon
Christmas
The Beatles
Drug overdose

3 clicks needed:

It appears that Kevin OD'ed on Christmas with the Beatles.

http://www.netsoc.tcd.ie/~mu/cgi-bin/shortpath.cgi?from=Kevin+Bacon&to=drug+overdose

I find it incredibly ammusing that Bukkake is only three clicks away from The Roman Catholic Church...

By way of the Japanese Language evidentally.

http://www.netsoc.tcd.ie/~mu/cgi-bin/shortpath.cgi?from=bukkake&to=catholic+church

Shortest path from You to Natalie Portman

1. You
2. Darth Vader
3. Natalie Portman

Shortest path from Natalie Portman to Hot Grits

1. Natalie Portman
2. Connecticut
3. African American
4. Grits
5. You

Shortest path from Natalie Portman to Bed

1. Natalie Portman
2. Arabic language
3. Bilabial consonant
4. Bed

Shortest path from You to Natalie Portman

1. You
2. Darth Vader
3. Natalie Portman

Shortest path from Natalie Portman to Hot Grits

1. Natalie Portman
2. Connecticut
3. African American
4. Grits
5. You

Shortest path from Natalie Portman to Bed

1. Natalie Portman
2. Arabic language
3. Bilabial consonant
4. Bed

Shortest path from You to Natalie Portman

1. You
2. Darth Vader
3. Natalie Portman

Shortest path from Natalie Portman to Hot Grits

1. Natalie Portman
2. Connecticut
3. African American
4. Grits
5. You

Shortest path from Natalie Portman to Bed

1. Natalie Portman
2. Arabic language
3. Bilabial consonant
4. Bed

Shortest path from Kevin Bacon to Profit

1. Kevin Bacon
2. Midwestern United States
3. Profit

The complete results are available here. Warning: this is both a very large file (~110MB) and in UTF-8.

Have you forgotten ISO-HTML? You see a lot of implementations of that nowadays.

You just need to find the right LaTeX packages. :)

Of course, depending on how complex it is, you could use built-in features.

If you live in Ireland (guessing from your email address), perhaps you should visit the largest research library in Ireland at Trinity College, Dublin. Non-members can make a case to be allowed to use the library.

Also, only an idiot would think that any human has ever experienced anything more than a millionth of a second of time dilation, even from orbiting the earth.

You are wrong.

See this figure from this journal article. The ISS is in a circular orbit with an altitude of about 360 km, hence a radius of about 6750 km. So clock aboard the ISS runs slower than it would on the surface of the earth by a factor of (1 - 300 * 10^-12). This comes out to about one millionth of a second per hour.

If you know the orbital speed of the ISS, you can estimate this yourself. Time dilation described by special relativity goes like gamma = sqrt(1-v^2/c^2) which is about (1 - 0.5 * v^2 / c^2) plus terms of order O(v^4/c^4). So we find that the fractional difference in rates due to time dilation is about about 330 * 10^-12.

This does not include the effects of gravity, which is not described by special relativity. That's why the previous answer was different. But you can also estimate this yourself, without really needing to know general relativity:

The frequency of a photon constitutes a clock. The energy of a photon is proportional to its frequency. A photon of energy E at radius 6750 km which travels downward to radius 6400 km will have suffered a loss in potential energy proportional to (1/r). So it's reasonable to guess that the energy of the photon at the earth's surface will have increased (a.k.a. gravitational blueshift) by an amount of about (1 + 306* 10^-12) So we recover (330 - 36) * 10^-12 = 294 * 10^-12 as the effective rate of time dilation for an astronaut on the ISS.

In fact, the gravitational redshift or blueshift predicted by general relativity is slightly different from the expression above, but for a small shift, this is a valid approximation.

These effects are real and have been observed. In fact, it is necessary to take them into account to design a working satellite GPS system. This article has more details.

Also, only an idiot would think that any human has ever experienced anything more than a millionth of a second of time dilation, even from orbiting the earth.

You are wrong.

See this figure from this journal article. The ISS is in a circular orbit with an altitude of about 360 km, hence a radius of about 6750 km. So clock aboard the ISS runs slower than it would on the surface of the earth by a factor of (1 - 300 * 10^-12). This comes out to about one millionth of a second per hour.

If you know the orbital speed of the ISS, you can estimate this yourself. Time dilation described by special relativity goes like gamma = sqrt(1-v^2/c^2) which is about (1 - 0.5 * v^2 / c^2) plus terms of order O(v^4/c^4). So we find that the fractional difference in rates due to time dilation is about about 330 * 10^-12.

This does not include the effects of gravity, which is not described by special relativity. That's why the previous answer was different. But you can also estimate this yourself, without really needing to know general relativity:

The frequency of a photon constitutes a clock. The energy of a photon is proportional to its frequency. A photon of energy E at radius 6750 km which travels downward to radius 6400 km will have suffered a loss in potential energy proportional to (1/r). So it's reasonable to guess that the energy of the photon at the earth's surface will have increased (a.k.a. gravitational blueshift) by an amount of about (1 + 306* 10^-12) So we recover (330 - 36) * 10^-12 = 294 * 10^-12 as the effective rate of time dilation for an astronaut on the ISS.

In fact, the gravitational redshift or blueshift predicted by general relativity is slightly different from the expression above, but for a small shift, this is a valid approximation.

These effects are real and have been observed. In fact, it is necessary to take them into account to design a working satellite GPS system. This article has more details.

Newton's _laws_ were and still are wrongly named.

Newton's Laws are perfectly fine, the first: an object in motion will continue in motion until acted upon by an outside force is perfectly consistent with General (and of course Special) Relativity, although it's very difficult to talk about acceleration in Special Relativity (see Newton's Second Law)

Newton's Second Law: that the change in motion is proportional its change in momentum (which is the product of mass (or inertia) and velocity) is very difficult to state in either General Relativity or Special Relativity. This is because a decision must be made about which observer's concept of time to use to take the time derivative of momentum and this in general the notion of force is avoided in relativity. But it's there usually referred to as the Minkowski Force.

Newton's Third law, Every reaction is met by an equal and opposite reaction is simply conservation of energy and is not violated in any classical theory, of which relativity both General and Special are.

What Newton was wrong about (and it's not really fair to call him wrong since he lacked a theory of electrodynamics and accurate measurements of the speed of light and the fact that it's independent with respect to the motion of observers so it's better to call him ignorant) was instantaneous action at a distance as implied by his theory of gravitation (Special Relativity gets around the instaneous part, General Relativity explains the action at a distance part, but not in a fashion consistent with the best theory of electromagnetic interactions QED) and the nature of light as a particle. Given that like Einstein's annus mirabilis, Newton's major achievements in physics and math were accomplished over the period of a little more than a year before he even finished the equivalent of his undergraduate degree I think we can cut him a little slack. After all, what world changing intellectual feats did you accomplish this summer?

The problem with the idea that Newton was wrong as opposed to under-informed and that Einstein made Newton's theories irrelevant in some fashion is what leads Intelligent Design proponents to claim a similar supercession of Evolution via Natural Selection claiming they are the Einstein's to Darwin's Newton. Since Einstein is more or less the Paul to Newton's Moses (or the Plato to Newton's Socrates although I think that's a poorer analogy) in the sense that he represents a fuller, different yet complementary and compatible ideology, it's ironic that IDers claim to bear the same relationship to Darwin.

This happened in Trinity College a few years ago, there were a few old AS400 Servers the Admins had forgotten about till one crashed and kill 3 of the main backend Databases with were running on them.

After 2 months of looking for the Servers, following a jungle of Cat5,Coax and AUX leads it turned out that there was some building work done about 6 years before in an old section of the College thats not been used anymore and the Servers were hidden in a room that had been blocked off behind a new wall that had been put in...?!!??!

Monad is also used in category theory
https://www.cs.tcd.ie/Robert.Byrne/CTDefns/Monad.h tml

Wow - I like this pic: sj9.jpg. Anyone got a larger version of it?

http://matrix.netsoc.tcd.ie/~64ndhi/SlashdotKazakh stan/

Document your application, requirements, constraints, and system interactions (what the engineer does). Then write the code (what the coder does). What you will quickly learn is that it's better to be the engineer than the coder.

Interestingly there are a number of formal languages to do this, some of them rather similar to programming languages. For example you can use an algebraic specification language like CASL - it provides a structured way to define datatypes, operations on datatypes, and the axioms that the types and operations need to obey for the requirements to be met (For the mathematicians out there: an implementation is then a (many-sorted) universal algebra, and a specification is a presentation). There are things like refinement calculus and theorem provers to help you refine your requirements into an ever more specific specifications. Once that is done the actual programming is pretty much monkey work: there are extremely specific bounds on every datatype, every function, to the point where it is merely a matter just doing what you're told. The interesting part happen with the initial requirements specification and the refinement and design of the specification.

I happen to like CASL, and chose it here because the the syntax is similar to programming languages, but it is far from the only, or even the most popular specification language. You could try Z, or VDM, or B-method, or OBJ3, or any of the myriad other languages out there. Formal specification languages ought to be far more widely used than they apparently are. Isn't it about time more "software engineers" started paying attention to them?

Jedidiah.

If EVERYONE has a computer in their car to help them avoid traffic jams, then it would be absolutely pointless.

The "Wardrop Equilibrium Principle": Under equilibrium conditions, traffic arranges itself in congested networks in such a way that no individual trip maker can reduce his path costs by switching routes.

If all trip makers perceive costs in the same way then the Wardrop Equilibrium Principle may be re-stated as follows: Under equilibrium conditions traffic arranges itself in congested networks such that all routes between any Origin / Destination pair have equal and minimum costs, while all unused routes have greater or equal costs.

Wardrop's Equilibrium Principle has caused many a graduate student taking a transportation engineering course in network optimization to take up drinking.

How about this then?
http://www.cs.tcd.ie/courses/ba/

Removing objects from images is an area of image processing research. Many papers have been written about such software (which has been converted into plugins for Photoshop in many cases).

Here's a link to some examples

Never mind - my goof...

While W3C has not made HTML a standard, the ISO and IEC apparently have standardised "a refinement of the World Wide Web Consortium's (W3C's) Recommendation for HTML 4.0 ... Documents which conform to this International Standard also conform to the strict DTD provided by the W3C Recommendation for HTML 4.01."

HTML is not a standard in the classic ISO/IEC sense

Here's a bookmarklet that will display two pages side-by-side. It's a trivial change to make it display two copies of the current page without prompting.

Posted anon for non-whore-action:

Quick scoop on multicast vs. unicast (what you are using now).

Here's a Stallman Stallman Lecture from Ireland a few months back.

I tend to thing MM games are going to be the killer app for interactive storytelling. If you think about it, there are really only three ways to do interactive content for MM games:

1. Create a fixed set of non-interactive content. Everyone in the game world does the same quests, reads the same dialog, fights the same big bad guy for the same reason. Alternately, a few people get to participate interactively, while the vast majority simply watch (or show up for the epic battle).
2. Employ humans to create custom content for each player. Figure out a way to do this for under $20 per player per month.
3. Programmatically create custom content for each player.

There's actually already quite a bit of work going on in this area. The most interesting approach I'm familiar with is Padraig Cunningham's work with case-base systems. In a nutshell, Cunningham proposes borrowing plot recipes from the russian structuralists. One then plugs existing NPCs into the appropriate roles (wise old man, bearer of gifts, etc). The system scales by allowing one NPC to play multiple roles in multiple simultaneous stories, so long as the roles don't conflict.

So, not unlike real life, your view of an NPC (as a dastardly villain, unexpected benefactor, or innocent in distress) depends on what you're doing when you meet that person.

For more information on Cunningham's work, check out his publications. In particular, the paper entitled "A Multiplayer Case Based Story Engine."

Personally, I'm working on a system for generating plot-rich city histories (via personality and relationship modeling). My goal is to get to a point where one could plop down a new town, set some parameters, and "age" the town n years (and get sensible personal relationships, family trees, interesting local history, street layouts, etc).

As a P.S. -- the sort of quote I had in mind, suggesting an affirmative answer is this:

assembly language programming is essential background for every computer science and electronic engineering student. It is, however, often considered an arcane and complex discipline because many first encounter it through the daunting instructions and registers of the Intel 8086 family.

Programming in a simple RISC architecture is very different due to the elegant and compact instruction set. Students of this text who have never programmed before and study it simultaneously with a course on a higher-level language report it is easier and more logical to program in assembly!

Richard is also giving a talk in Dublin on the 24th of May.