4 ms·

> 3. There's a higher-level agent still—again, still one per motor!—responsible for stopping at stations, which does this by biasing the collision agent to temp

by im3w1l 7y ago

> 3. There's a higher-level agent still—again, still one per motor!—responsible for stopping at stations, which does this by biasing the collision agent to temporarily think there's another train just far-enough away that it must stop where the station is in order to avoid it. This sounds clever in the worst sense of the word. Introducing dependencies and complexities for no reason. Want to increase safety margins from trains? Suddenly it doesn't stop correctly at stations any more.

derefr 7y ago
You don't change internal variables; you change top-level goal conditions (in imperative programming terms, the "test suite"), and retrain the system, and all the internal variables change together to find a new equilibrium. That's kind of... how ML works. It's how brains seem to work, too. (Think about the order in which you learn to do something like typing. Think about what "levels" of that learning that you need to practice over again, if you switch to a different keyboard layout.) Also, to be clear, this is already what subway systems do. And roombas. And a bunch of other types of robots. It turns out to work better, in practice, than the alternative (= networks of leaf-node controllers with individual top-down-issued config parameters, like computer networks are.) Although, they don't do it because it's an easy system to develop in. Subsumption is operationally robust—it continues to do the right thing in the face of failure of components, or even "subverted" components producing malicious input. This is a little important when you're a Mars rover whose firmware chips could be hit by gamma rays; but it's even more important when you're an organic lifeform with parasites constantly attempting to hijack your nervous system to their own ends (e.g. the Toxoplasma bacterium and the Cordyceps fungi, two cases where the host isn't strong enough to resist the hijacking. In the 99.999% of other cases of parasitic onslaught that you don't hear about, the host does still manage to "do the right thing" despite the parasite.)
- im3w1l 7y ago
  I didn't mean it to be a critique of the concept of subsumption itself, only your specific example. For instance having the train avoidance system provide a reference speed to the wheel controllers seems solid. Having the station stopper create fake trains (or having the train avoider create fake stations) does not seem robust. Would be better to have the station stopper set reference speed, and give the train avoider the authority to override it.

by im3w1l 7y ago

derefr 7y ago

You don't change internal variables; you change top-level goal conditions (in imperative programming terms, the "test suite"), and retrain the system, and all the internal variables change together to find a new equilibrium. That's kind of... how ML works. It's how brains seem to work, too. (Think about the order in which you learn to do something like typing. Think about what "levels" of that learning that you need to practice over again, if you switch to a different keyboard layout.) Also, to be clear, this is already what subway systems do. And roombas. And a bunch of other types of robots. It turns out to work better, in practice, than the alternative (= networks of leaf-node controllers with individual top-down-issued config parameters, like computer networks are.) Although, they don't do it because it's an easy system to develop in. Subsumption is operationally robust—it continues to do the right thing in the face of failure of components, or even "subverted" components producing malicious input. This is a little important when you're a Mars rover whose firmware chips could be hit by gamma rays; but it's even more important when you're an organic lifeform with parasites constantly attempting to hijack your nervous system to their own ends (e.g. the Toxoplasma bacterium and the Cordyceps fungi, two cases where the host isn't strong enough to resist the hijacking. In the 99.999% of other cases of parasitic onslaught that you don't hear about, the host does still manage to "do the right thing" despite the parasite.)

im3w1l 7y ago
I didn't mean it to be a critique of the concept of subsumption itself, only your specific example. For instance having the train avoidance system provide a reference speed to the wheel controllers seems solid. Having the station stopper create fake trains (or having the train avoider create fake stations) does not seem robust. Would be better to have the station stopper set reference speed, and give the train avoider the authority to override it.