3 ms·

That's a nice idea and it kind of works with the internal database. But in terms of FFI or other interactivity, you can't un-read bytes from an input stream or

by maweki 3y ago

That's a nice idea and it kind of works with the internal database. But in terms of FFI or other interactivity, you can't un-read bytes from an input stream or un-write to another process. That makes interoperability inherently imperative. My use case is, that you usually wouldn't un-move a robot. You want to re-plan from the current position, if an obstacle comes up. You sure as hell don't want to backtrack into an alternate plan from your original starting position.

YeGoblynQueenne 3y ago
>> My use case is, that you usually wouldn't un-move a robot. You want to re-plan from the current position, if an obstacle comes up. You sure as hell don't want to backtrack into an alternate plan from your original starting position. That's right, but I think if you backtracked that far, the planning should simply fail. Are we working on something similar? I'm using Inductive Logic Programming to learn robot plans. I don't know too much about planning but I reckon what we're learning are generalised plans (with an option to make them as specialised or general as needed). The project I'm on has started only this June so I'm not yet at the point where there's need to change a plan, but I've done some thinking about it. I might be over-optimistic, but I think it's a matter of putting plans on a stack and allowing them to be carried out in LIFO order. Then, if the original plan (the first to be put on the stack) doesn't work anymore, you just backtrack to make another plan from the current position, after checking the current state of the world. OK, I don't know if that makes any sense to you. Does it?
- maweki 3y ago
  > Are we working on something similar? It's not the first time us two have this kind of discussion. > Then, if the original plan (the first to be put on the stack) doesn't work anymore, you just backtrack to make another plan from the current position, after checking the current state of the world. Sure. That's the replanning. But actually you could backtrack into a plan you've already got that has the same prefix as the plan you've already chosen. Presumably a different plan differs from exactly this position and avoids the obstacle that made the current plan fail at that point. You'd have to keep track of the movements you've done. But as the plans are generated lazily, both concepts ('replanning' and 'choosing one of the original plans that hasn't been "superseded by reality" yet') might actually be the same.
  - YeGoblynQueenne 3y ago
    >> It's not the first time us two have this kind of discussion. Oh, I think I remember us talking about ILP. Sorry, I didn't recognise your username. Without avatars on HN I find it hard to remember who I've interacted with. I don't think we had talked about robotics or planning though. Anyway now I'll remember you :) >> Sure. That's the replanning. But actually you could backtrack into a plan you've already got that has the same prefix as the plan you've already chosen. Presumably a different plan differs from exactly this position and avoids the obstacle that made the current plan fail at that point. You'd have to keep track of the movements you've done. But as the plans are generated lazily, both concepts ('replanning' and 'choosing one of the original plans that hasn't been "superseded by reality" yet') might actually be the same. I think I see what you mean. There's certainly a problem with backtracking all the way to the point where a plan failed only to pick up again from that point- and probably fail again. I don't think I can reason about this from first principles. I'd have to try it out and see what works and what doesn't. EDIT: I went back and found our previous discussion. Hi again.

by maweki 3y ago

YeGoblynQueenne 3y ago

>> My use case is, that you usually wouldn't un-move a robot. You want to re-plan from the current position, if an obstacle comes up. You sure as hell don't want to backtrack into an alternate plan from your original starting position. That's right, but I think if you backtracked that far, the planning should simply fail. Are we working on something similar? I'm using Inductive Logic Programming to learn robot plans. I don't know too much about planning but I reckon what we're learning are generalised plans (with an option to make them as specialised or general as needed). The project I'm on has started only this June so I'm not yet at the point where there's need to change a plan, but I've done some thinking about it. I might be over-optimistic, but I think it's a matter of putting plans on a stack and allowing them to be carried out in LIFO order. Then, if the original plan (the first to be put on the stack) doesn't work anymore, you just backtrack to make another plan from the current position, after checking the current state of the world. OK, I don't know if that makes any sense to you. Does it?

maweki 3y ago
> Are we working on something similar? It's not the first time us two have this kind of discussion. > Then, if the original plan (the first to be put on the stack) doesn't work anymore, you just backtrack to make another plan from the current position, after checking the current state of the world. Sure. That's the replanning. But actually you could backtrack into a plan you've already got that has the same prefix as the plan you've already chosen. Presumably a different plan differs from exactly this position and avoids the obstacle that made the current plan fail at that point. You'd have to keep track of the movements you've done. But as the plans are generated lazily, both concepts ('replanning' and 'choosing one of the original plans that hasn't been "superseded by reality" yet') might actually be the same.
- YeGoblynQueenne 3y ago
  >> It's not the first time us two have this kind of discussion. Oh, I think I remember us talking about ILP. Sorry, I didn't recognise your username. Without avatars on HN I find it hard to remember who I've interacted with. I don't think we had talked about robotics or planning though. Anyway now I'll remember you :) >> Sure. That's the replanning. But actually you could backtrack into a plan you've already got that has the same prefix as the plan you've already chosen. Presumably a different plan differs from exactly this position and avoids the obstacle that made the current plan fail at that point. You'd have to keep track of the movements you've done. But as the plans are generated lazily, both concepts ('replanning' and 'choosing one of the original plans that hasn't been "superseded by reality" yet') might actually be the same. I think I see what you mean. There's certainly a problem with backtracking all the way to the point where a plan failed only to pick up again from that point- and probably fail again. I don't think I can reason about this from first principles. I'd have to try it out and see what works and what doesn't. EDIT: I went back and found our previous discussion. Hi again.