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oktober 16, 2006

Lite länkar

Några länkar som sparats på Bloglines för att de befunnits intressanta och ska kikas (vidare) på.


Guardian Unlimited: Oh no, not Steely Dan again


Steven Levy really liked Steely Dan, but so too, it seemed, did his iPod. Like a lot of people, he began to wonder about its shuffle - was the random function really random or a result of dirty tricks, blunders... or even telepathy?

Cf:
Guardian Unlimited: The spice of life
Wikipedia: Shuffle

Russ Abbott: Emergence Explained


Emergence (macro-level effects from micro-level causes) is at the heart of the conflict between reductionism and functionalism. How can there be autonomous higher level laws of nature (the functionalist claim) if everything can be reduced to the fundamental forces of physics (the reductionist position)? We cut through this debate by applying a computer science lens to the way we view nature. We conclude (a) that what functionalism calls the special sciences (sciences other than physics) do indeed study autonomous laws and furthermore that those laws pertain to real higher level entities but (b) that interactions among such higher-level entities is epiphenomenal in that they can always be reduced to primitive physical forces. In other words, epiphenomena, which we will identify with emergent phenomena, do real higher-level work. The proposed perspective provides a framework for understanding many thorny issues including the nature of entities, stigmergy, the evolution of complexity, phase transitions, supervenience, and downward entailment. We also discuss some practical considerations pertaining to systems of systems and the limitations of modeling.


Peter Woit (Not Even Wrong):
Navier-Stokes Equation Progress?
En lång diskussion om ett matematiskt paper där paper-författaren snabbt tillkännagör att artikeln är felaktig och drar tillbaka den för komplettering.

The Probability That I Alone Will Decide an Election

Ivars Peterson: Pancake Sorting

MathFactor: (MP3 podcast):
Ett svar till "Which way leads out of the forest of Liars & Truth-tellers?" samt ett nytt problem.


Mind Hacks: Average girls are hot


Seed Magazine has an article on recent research published in Psychological Science that suggests that average faces are more attractive because they are easier for the brain to process.

....




Daniel Lemire, Owen Kaser:
One-Pass, One-Hash n-Gram Statistics Estimation


In multimedia, text or bioinformatics databases, applications query sequences of n consecutive symbols called n-grams. Estimating the number of distinct n-grams is a view-size estimation problem. While view sizes can be estimated by sampling under statistical assumptions, we desire an unassuming algorithm with universally valid accuracy bounds. Most related work has focused on repeatedly hashing the data, which is prohibitive for large data sources. We prove that a one-pass one-hash algorithm is sufficient for accurate estimates if the hashing is sufficiently independent. To reduce costs further, we investigate recursive random hashing algorithms and show that they are sufficiently independent in practice. We compare our running times with exact counts using suffix arrays and show that, while we use hardly any storage, we are an order of magnitude faster. The approach further is extended to a one-pass/one-hash computation of n-gram entropy and iceberg counts. The experiments use a large collection of English text from the Gutenberg Project as well as synthetic data.



Jurij Leskovec, Lada A. Adamic, Bernardo A. Huberman:
The Dynamics of Viral Marketing


We present an analysis of a person-to-person recommendation network, consisting of 4 million people who made 16 million recommendations on half a million products. We observed the propagation of recommendations and the cascade sizes, which can be explained by a stochastic model. We then established how the recommendation network grows over time and how effective it is from the viewpoint of the sender and receiver of the recommendations. While on average recommendations are not very effective at inducing purchases and do not spread very far, there are product and pricing categories for which viral marketing seems to be very effective.



Google Tech Talk. Nuno Vasconcelos: Using Statistics to Search and Annotate Pictures

Google Tech Talk. Karl Fogel: The Surprising History of Copyright and What It Means For Google

Google Tech Talk: David Pollak Ruby Sig: How To Design A Domain Specific Language


Timothy C. Marzullo, Edward G. Rantze,, Gregory J. GageMichigan, Ann Arbor
Stock Market Behavior Predicted by Rat Neurons (PDF)
Via Improbable Research


AustenBlog: 1940 PRIDE AND PREJUDICE to be released on Region 1 DVD October 10


numb3rs blog: Zero point energy, cycloids
Om senaste numb3rs-avsnittet (SE3,avsnitt 4 "Mole"). Spoilervarningar.
Cf:
numb3rs blog: Face Recognition Algorithms
Computational Complexity: Numb3rs of Collaborators


Statistics, Damn Statistics, and Lies


IEEE Spectrum: Modeling Terrorists


New simulators could help intelligence analysts think like the enemy.



NPR: Is String Theory Unraveling?


NPR's Scott Simon talks with "Math Guy" Keith Devlin about two new books that call into question the entire idea of string theory. The theory states that tiny vibrating strings make up everything, but some scientists say there is no way to prove or disprove it.

Cf följande två böcker
Peter Woit (bloggen Not Even Wrong, se även ovan)Not Even Wrong - The Failure of String Theory And the Search for Unity in Physical Law
Lee Smolin: Trouble With Physics


New Scientist: Do cancer cells cooperate with each other?


An analysis of how cells in a tumour cooperate has provided a unique insight into the evolution of cancer, and may lead to new treatments.

It makes use of "game theory" – the mix of mathematics and economics theory that has been invaluable in understanding how cooperation can evolve in animal societies, even when individuals are selfish.

Robert Axelrod, a political scientist at the University of Michigan in Ann Arbor, US, a leader in applying game theory to evolutionary biology, has now turned his attention to cancer.




Harvard University: A Celebration of the Achievements of Nobel Laureate: Thomas C. Schelling (video, kräver RealPlayer 10.5).


Damn Interesting: The Baader-Meinhof Phenomenon


Baader-Meinhof is the phenomenon where one happens upon some obscure piece of information– often an unfamiliar word or name– and soon afterwards encounters the same subject again, often repeatedly. Anytime the phrase "That's so weird, I just heard about that the other day" would be appropriate, the utterer is hip-deep in Baader-Meinhof.


Posted by hakank at oktober 16, 2006 06:47 EM Posted to Diverse vetenskap