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Could markets be called optimization proccesses?
shadow10

Water flowing downhill is an optimisation process.

Do you mind telling me what does that optimise? In other words, what is the objective function?

I've never seen an academic article saying that the world is maximising entropy (in the thermodynamic sense). I understand that the second law of thermodynamics hints that entropy is a fairly closed system should increase over time.

When a process (rather) consistently increases (or decreases) the value of a variable, it doesn't necessarily optimise it! Like when you see a nation's positive GDP growth from y... (read more)

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0timtyler
The phenomenon isn't always "efficient" at dissipating entropy - because of constraints imposed by physical law. Also, in general, optimisation processes are not guaranteed to find the "optimal outcome" - due to local maxima. I am not making the idea of entropy maximisation up - there's a big literature about it dating back to 1922. Check my references.
0timtyler
Right. Well, I already gave some references about that further up the thread - these ones: * Dewar, R. C., 2003, "Information theory explanation of the fluctuation theorem, maximum entropy production and self-organized criticality in non-equilibrium stationary states," J. Phys. A: Math.Gen. 36: 631-41. * Dewar, R. C., 2005, "Maximum entropy production and the fluctuation theorem," J. Phys. A: Math.Gen. 38: L371-L381. However, there are a large number of other such articles. E.g. see: * Royal Society "Theme Issue" 'Maximum entropy production in ecological and environmental systems: applications and implications' compiled and edited by Axel Kleidon, Yadvinder Malhi and Peter M. Cox May 12, 2010; 365 (1545) - (17 papers) * Paltridge, Garth W. 1975, Global Dynamics and Climate – A System of Minimum Entropy Exchange. Q. J. R. Meteorol. Soc. 101, 475-484 * Paltridge, Garth W. 1978, The Steady State Format of Global Climate. Q. J. R. Meteorol. Soc. 104, 927-945 * Paltridge, Garth W., 1969 - Climate and thermodynamic systems of maximum dissipation For more introductory material, perhaps see: * Whitfield, John, Survival of the Likeliest * Whitfield, John, Complex systems: Order out of chaos ...and for more references, perhaps try the ones on: http://originoflife.net/bright_light/
0Perplexed
While I generally agree with you in this debate, and disagree with Tim Tyler's claims that spontaneous dissipation of free energy exemplifies Nature's optimization of entropy production, I have to agree with ata. There is an important distinction between an optimization problem and an optimization process. And the distinction is definitely not that the process generates the solution to the problem. Yep, that is what is happening, alright. But this isn't quite as disreputable as you make it sound. Take, for example, biological evolution under natural selection - the canonical example of an 'optimization process' as the phrase is used here. R.A. Fisher proved that (under the admittedly unrealistic assumption of an unchanging environment) the average 'fitness' of the organisms in a population subject to natural selection can only increase, so long as the mutation rate is moderate. So what is 'fitness'? Well, it is an 'objective function' which we generate from the phenomenon - the fitness of an individual organism is simply a count of surviving offspring and the fitness of a 'type' is the average fitness of the individuals of that type. So, this 'fitness' can only increase. But there is no guarantee that the process generating the increase is efficient, nor that some 'optimal' level of 'fitness' will ever be reached. Nonetheless, the local usage designates natural selection as an 'optimization' process. We are aware that we are flirting with teleological language, here, but it is only a flirtation. We know what we are doing. We are not in danger of being seduced.
0ata
I'm pretty sure you're still not using the word "optimization" in the sense of the phrase "optimization process" as used on Less Wrong. An optimization process doesn't have to be a process that maximizes an explicitly-defined utility function; the function can be implicit in its structure or behaviour. It's not really the same as the sense of "optimization" described in the aforelinked Wikipedia article, which isn't the subject of this discussion post. The terminology of "optimization processes" is used to analyze dynamics acting within a system.
Could markets be called optimization proccesses?
shadow10

Water flowing downhill is an optimisation process. Do you mind telling me what does that optimise? In other words, what is the objective function? Water flowing downhill because of gravity. It needs not optimise anything.

Of course, certain intrinsic properties may make some non-living things survive better than other (long half lives, water resistance, etc). But you don't need to give them any objective as though they have a mind. When you say 'optimisation,' you ascribe one more objective to something within a set of constraints, and by doing this you... (read more)

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0timtyler
In a word, entropy. Water flowing downhill does optimise a function, though. The laws of physics are microscopically reversible - and so are exactly as compatible with water flowing uphill as down. Water flows downhill because of statistical mechanics. You are not using the word 'optimization' in its mathematical sense - whereas I am.
Could markets be called optimization proccesses?
shadow00

Konkvistador says:

Evolution is a[n] optimization process.

Evolution is too slow. Moreover, evolution embraces the greedy algorithm:

evolution has no foresight, and only takes the next greedy local step.

Evolution works but that doesn't mean it is optimal. It is, I believe, inefficient.

Timtyler says:

The whole world is an optimisation process.

Huh? Does that include the human mind? The horrible geography and weather in some places of the world where very few species can survive? Natural disasters?

This post (anthropomorphic optimism) may interest you.... (read more)

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-2timtyler
Yes, all of those. Water flowing downhill is an optimisation process. We understand the microscopic mechanisms in some cases - for example, the ones spelled out by Dewar (see refs below) - and it has long been understood that natural selection applies to many non-biological systems. You are suggesting that my views on this topic are anthropomorphic?!? Uh, they are the facts of the matter. * Dewar, R. C., 2003, "Information theory explanation of the fluctuation theorem, maximum entropy production and self-organized criticality in non-equilibrium stationary states," J. Phys. A: Math.Gen. 36: 631-41. * Dewar, R. C., 2005, "Maximum entropy production and the fluctuation theorem," J. Phys. A: Math.Gen. 38: L371-L381.
New Year's Predictions Thread (2011)
shadow10

Just some questions.

1) Why do most probabilities here in percentage divisible by 5? Is there any reason that they be, I assume, rounded to the nearest 5? If this is the case, the 65% probability means "between 62.5 and 67.75", right? Um, maybe not. I bet some people here round the probabilities to the nearest 10.

2) I would love to see some kind of distribution as well. Can we say something like:

I am 90% confident that the probability that event X happens is between 35% and 50%, but my best bet is 45%.

The distribution is skewed here, and it ... (read more)

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4Spurlock
Hello shadow, Welcome to LessWrong! I think the answers to your questions are as follows: 1) Working out exact probabilities for these kinds of predictions is unfeasible, so we approximate. Rounding to the 5 seems natural to a lot of us, and (I expect) it automatically conveys the approximate-ness of the prediction to most people. 2) Probability is in the mind. Therefore, giving a distribution of probabilities is just a way of saying "I am uncertain about how uncertain I am". 4) Don't think I understand this one, although this might qualify and/or interest you.