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Traffic Prediction with Advanced Graph Neural Networks

deepmind.com

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Re: Traffic Prediction with Advanced Graph Neural Networks

#41

Post by mwc »

2bitencryption wrote: post #5

Google Map's traffic prediction has always led me to a very curious question: Clearly Google Maps has the ability to turn into a feedback loop. Traffic exists -> people use Google Maps to find better routes -> traffic is modified due to people taking alternate routes -> new traffic emerges. So my question is: what is Google Maps traffic optimizing for? The best traffic experience for User 3982274, or the best traffic…

This is how Uber matches trips[0]. Optimising not for the fastest pick up for any one rider, but to reduce the total time of arrival in the whole network.

[0] http://blogs.cornell.edu/info2040/2019/10/23/uber-ride-shari...

Re: Traffic Prediction with Advanced Graph Neural Networks

#42

Post by lr4444lr »

2bitencryption wrote: post #5

Google Map's traffic prediction has always led me to a very curious question: Clearly Google Maps has the ability to turn into a feedback loop. Traffic exists -> people use Google Maps to find better routes -> traffic is modified due to people taking alternate routes -> new traffic emerges. So my question is: what is Google Maps traffic optimizing for? The best traffic experience for User 3982274, or the best traffic…

Doesn't that already happen as a corollary of a greedy per user optimization? Each marginal car on the best course slows down the traffic, ergo weighting it slightly lower vs. alternatives. Isn't GMaps just filling out the best routes first?

Re: Traffic Prediction with Advanced Graph Neural Networks

#44

Post by layoutIfNeeded »

CyberDildonics wrote: post #19
layoutIfNeeded wrote: post #16

Earlier quoted context omitted.

That's definitely not how it works. Traffic is a nonlinear dynamical system with all sorts of non-intuitive coupling between various components.

What's the difference between a dynamic system and a dynamical system?

A dynamical system (https://en.wikipedia.org/wiki/Dynamical_system) is basically a bunch of (continuous / discrete) variables whose evolution is governed by a set of (differential / difference) equations. E.g. a pendulum is a dynamical system whose state can be described with a single variable 𝜃 (the angle of the pendulum), governed by the differential equation:

𝘥²𝜃/𝘥t² + g/l sin(𝜃) = 0

(where g is the gravitational acceleration and l is the length of the pendulum)

Dynamical systems whose behaviour is linear are kinda well-behaving and easy to analyse. (linear in this context means that the system's response to a linear combination of inputs will be the same as the linear combination of its responses to the individual inputs) Non-linear systems on the other hand behave chaotically, producing wildly different responses to slight differences in their inputs.

I'm not sure what a "dynamic system" is though.

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