5 ms·
Very much like the $5000 books on Amazon where the algorithms are anticipating flipping an existing listing. Congrats on winning this round! The next step might
by ChuckMcM 5y ago
Very much like the $5000 books on Amazon where the algorithms are anticipating flipping an existing listing. Congrats on winning this round! The next step might be interesting which would be to go back and re-purchase the Condo once the price corrects to the 'real' price and bank the difference.
I have read this article and the one before it and it sounds very much like some folks who fell in love with their own idea and got early feedback that it was "working", went all in and never checked to see if it was still working.
The lesson should have been, "When you perturb an emergent system, never assume that the current state is the new steady state."
The most interesting thing for me back when I was in college was a discussion on of the professors on feedback systems gave on LA's freeway systems. There are three major interconnected freeways, 405, 110, and 10 which at the time formed a triangle. Now there is the 105 which cuts off the tip so perhaps a smaller triangle. The professor shared a paper that tracked "brake waves" which were aggressive braking maneuvers that would "propagate" backwards on crowded freeways. The paper showed that at the right time of day, an aggressive braking on any of these three segments could result in your own braking wave to "lap around" and hit you again. Sort of a ringing of the system.
This sort of effect can be present in any system that isn't centrally organized but is instead a result of the interactions within the system. Buying and selling real estate is such a system, especially when you are a 'market maker' in that system.
There are a lot of papers on how HFT trading algorithms interfere (both constructively and destructively) with each other on wall street exchanges. Just interesting stuff in my opinion.
- iab 5y agoTraffic fascinated me - please post a link to that paper
- ChuckMcM 5y agoI will see if I can find it, not all papers published in the 80's are online. (and I just looked the professor is emeritus at USC now but still around so I'll send him the question too)
- ahmadss 5y agoyes please do find that paper (or the name of the professor)!
- ChuckMcM 5y agoI believe the paper's author was Newell, but the USC professor was Dr. Kuehl (Dr. Cool :-). He was teaching Linear Systems when I was there and always had some really great "real world" applications of the stuff we were learning.
- iab 5y agoI would really appreciate it
- vba 5y agoAppreciate the effort
- ChuckMcM 5y agoOkay, so I'm pretty sure it was done by G.F. Newell (UC Berkeley) I haven't found the paper we discussed in '82 but he went on to publish a 3 part description of traffic dynamics called "A simplified theory of kinetic waves in highway traffic" and reading through the abstracts for those it covers the same territory we were discussing in the systems class I was taking at the time.
- throwaway2037 5y agoDoes this help? https://www.sciencedirect.com/science/article/abs/pii/019126159390038C# https://www.sciencedirect.com/science/article/abs/pii/019126...! A simplified theory of kinematic waves in highway traffic, part I: General theory Also: https://www.sciencedirect.com/science/article/abs/pii/019126159390039D# https://www.sciencedirect.com/science/article/abs/pii/019126...! A simplified theory of kinematic waves in highway traffic, part II: Queueing at freeway bottlenecks
- ChuckMcM 5y agoSo Dr. Kuehl reminded me that he didn't teach me Linear Systems, he was teaching Electromagnetics at the time. (And no I don't know how I could confuse the two)
- ralston3 5y agoYea this is super interesting
- nfzOndjy 5y agoCan you recommend a few of those hot papers? I would love to read about that more.
- WalterBright 5y agoI knew about the brake wave back in 1980, as I could see it on I405 on my way home from work. Due to a curve in the highway, I could see about 3 miles ahead. The wave heading towards me was pretty obvious. I found I could "break" the wave by letting a gap grow in front of me that would absorb the wave, and I wouldn't have to brake to a stop (and so my clutch would last longer). It never occurred to me to write a paper about it :-)
- xapata 5y agoA good example of why allowing for stress tolerance can make a system more efficient in the long run.
- fspeech 5y ago"by letting a gap grow in front of me that would absorb the wave" would cause the freeway to carry fewer cars if everyone does it. My oldest one used to argue with me on this point when I asked him to keep a bigger gap from the car in the front for safety reasons.
- mavhc 5y agoNot if they all go faster. The human induced delay is the problem. Plus it causes accidents, which really slows down the system.
- hbarka 5y agoEver since driving an electric car, I have come to believe that a gas-throttle car’s laggy response during stop and go traffic may be responsible for the elasticity of the delay propagation. From zero, a piston pumper goes through a complicated series of windups which seems like days compared to an electric motor.
- grepfru_it 5y agoThrottles have only become drive by wire over the last 15 years, prior to that it was cable actuated and was instantaneous. Like a lawnmower. One could argue carburetor cars were even (a fraction of a second) more responsive. Also if you WOT a modern car you get the instant response without the ecu calculating pedal angle, comparing to accelerator history, humidity factors etc etc but kiss fuel efficiency bye bye. There are mods and tunes that reprogram the fuel map to cut out this processing time I also drive a big turbo family sedan and am used to saying 2 Mississippi before the engine pulls at full boar
- foogazi 5y agoYour comment on traffic reminded me of this article I read a long time ago about how to clear up “traffic waves”: http://trafficwaves.org/trafexp.html http://trafficwaves.org/trafexp.html
- snovv_crash 5y agoBrake waves happen because people brake harder than they accelerate afterwards. If you have enough following distance to brake gently, then hit the gas hard afterwards, and if everyone did this, then the waves would never appear.