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PageRank Algorithm Applied To the Food Web
An anonymous reader brings word of a new application for PageRank, Google's link analysis algorithm: monitoring the food web in an ecosystem. A team of researchers found that a modified version of PageRank can predict with great accuracy which species are vital to the existence of others. Quoting:
"Every species is embedded in a complex network of relationships with others. A single extinction can cascade into the loss of seemingly unrelated species. Investigating when this might happen using more conventional methods is complicated, as even in simple ecosystems, the number of combinations exceeds the number of atoms in the universe. So, it would be impossible to try them all. Co-author Dr. Stefano Allesina realized he could apply PageRank to the problem when he stumbled across an article in a journal of applied mathematics describing the Google algorithm. 'First of all, we had to reverse the definition of the algorithm. In PageRank, a web page is important if important pages point to it. In our approach, a species is important if it points to important species.'"
first post
Pagerank is just a repeated application of a transformation matrix. It has the effect of running a Markov model (a way to model discrete states) until there is convergence. He just used a Markov model the way that it is supposed to be used...
I dont get it... what's notable here?
Looks like i am the first to comment
What factorial does it take to equal that number? I know that its very easy in math to get numbers that large, but this wasn't a place I expected to find it.
FanFictionRecs.net
they didn't use Pigeon Rank on the food web.
A species is more important if it points to my stomach.
Also see my upcoming research topic:
Bioinformatic Algorithm for Standard Texan-Americans with Retro-Dissonant Suppositions
I expect to prove that BASTARDS are essential to the American way of life.
Now, if only they could find a way to use PageRank to solve the underlying problem - human overpopulation - we might finally be on the way to realistically saving all the endangered species. As it is, without solving that 800-pound-gorilla problem, all we can do is manage to keep them on life support for a few decades. Does anyone remember 'Silent Running'? We're headed for a scenario that will require us shipping a whole lot more than just trees and plants out to the orbit of Jupiter.
In some respect, an economy can be considered as a sort of ecology. If this research holds up, it would be interesting to do the same sort of analysis to rank the importance of industries and occupations. Which ones are necessary and vital and which ones (MPAA?) can be discarded without harm or even with benefit to the rest of the ecology.
And why?
In PageRank, a web page is important if important pages point to it. In our approach, a species is important if it points to important species.'"
The difference is, its pretty obvious to a human if a page is important. On the other hand there are a lot of species that we don't know if they are important or not. So how do we know what the "important" species are? Other than humans, we don't know of any real "important" species. Could the ecosystem survive without X? Theres no way we can really know that.
Taxation is legalized theft, no more, no less.
I've often been annoyed by the excessive focus on the iconic and popular species in many endangered species awareness campaigns. It is easy to say "we are spending a million dollars on protecting a worm?" in Congress, but when more renowned species like a hammerhead shark variety are endangered, they will naturally get more attention. Now scientists can defend their case for funding by pointing to this algorithm.
Have you learned nothing from history? We can know if an ecosystem survives without certain members.
It just isn't a good idea to experiment.
That's interesting, because most americans don't care about preservation.
My proof?
Wal-mart (and the associated industries that support low prices).
Sure, save the whales/sharks/pandas/worms. But I better get my tampico for 0.34$/bottle and jeans for $4.99 so I can afford to help out.
Pagerank is one of the most overblown "algorithms" ever. The way people talk about it you'd think it ranks up there with Fourier analysis or orbit determination. Pagerank is little more than a popularity contest - American Idol phone voting on steroids. If you need a general idea of what's going on, searching on Google's okay. If you want more substance better go for a specialist search engine.
Applying this to food I expect McDonalds to be ranked very high and fine dining to be ranked as rubbish.
Yeah go on mod me as troll, because *sarcasm* a rational person couldn't possible hold this opinion...
These posts express my own personal views, not those of my employer
I would have thought that an animal-based algorithm such as PigeonRank would be more applicable to this problem.
The World Wide Web is dying. Soon, we shall have only the Internet.
In the context of being an important part of the web, what is the page rank for the species homo sapiens?
The pagerank algorithm is better understood as a kind of Eigenvector Centrality Measure.
See http://en.wikipedia.org/wiki/Eigenvector_centrality#Eigenvector_centrality
Meaning it is not new as a method by itself, but applying it to the linking-structure of the WWW in order to produce
relevant documents for a query, was new. I think it is fair to say that the Google Pagerank matters very little, outside of being able to rank otherwise
not-comparable search results.
And so it is better to state that "a specialized Eigenvector Centrality Measure can predict with great accuracy which species are vital to the existence of others" instead of "a modified version of PageRank can predict with great accuracy which species are vital to the existence of others". One can see that also when one realizes that these biologists have no query, no search, no equivalent of search keywords.
On the other hand, when the post says "Co-author Dr. Stefano Allesina realized he could apply PageRank to the problem when he stumbled across an article in a journal of applied mathematics describing the Google algorithm." -- I guess he might have found the method through the Google name.
Stephan
http://stephan.sugarmotor.org
Awesome, now we know which species we can let go extinct!
Property is theft.
NO SHIT!
That is the whole damn point of this analysis, to determine popular food chains between all the animals to see the ones that would cause the largest impact in all the species.
If McDonalds suddenly died, the reverberations it would cause in the human food chain would be crazy!
Yes, the humans will just start targeting Burger King more, but they will end up going through a horrible time as well as they are filled to capacity and end up running out of stock quicker.
By the time they gather enough monies to either build new buildings or buy more stock, a significant amount of their regular customers would probably be pissed off by them running out of stock so much.
Pizza hut doesn't even come in to the argument, it is already dead. (in your average MKer or BKer, "pizzas, ewck")
Sure, "fine dining" might gain some popularity, but it would be very low percentage, like less than 10% increase on average.
There is absolutely nothing wrong with using what is basically a popularity algorithm to determine links like this.
But i can certainly see your criticism since it doesn't show the most information when it comes to how important a species is.
It could be improved to the point where it isn't so much as a food chain, but a verb chain, THIS would be a million times more useful, there are many verbs that animals do that can heavily influence other species, like bees as the best example i can think of.
Also, i hate DFDs...
This could be used to predict which projects are essential to open source and free software.
Certainly this is an additional tool that can be used to explore Lovelock's Gaia hypothesis. If other elements were included in the web of interactions such as atmospheric and dissolved CO2, the actions of rocks it might provide a further insight into global warming and what we should be looking at the mitigate it.
Where do you think low prices come from? Minimum wage in countries like china is pennies a day. Exploitation, really. And encouraging exploitation of people leads to exploitation of other resources. I think there is a hole in your thinking. Or maybe you've never thought about why walmart can sell things so cheap.
I am a representative of an important species and if I point to a web page it becomes important?
How long do I have to point at a certain page to put it on top of Google search results.
Corrected that for you
So what happens when this algorithm determines humans are the least important species to the ecosystem?