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Are we certain that well-trained human players are not doing search? It's possible that a search subnetwork gets "compiled without debugger symbols" and the own

Are we certain that well-trained human players are not doing search? It's possible that a search subnetwork gets "compiled without debugger symbols" and the owner of the brain is simply unaware that it's happening.

gwern 6y ago
I'm not sure why YeGoblynQueenne thinks this is such a mystery. (This is not the first time I've been puzzled by their pessimism on HN.) There is no mystery here: AlphaZero shows that you can get superhuman performance by searching only a few ply by sufficiently good pattern recognition in a highly parameterized and well-trained value function, and MuZero makes this point even more emphatically by doing away with the formal search entirely in favor of an more abstract recurrent pondering. What more is there to say?
- YeGoblynQueenne 6y ago
  MuZero performs a "formal search". In many more ways than one, for example optimisation is still a search for an optimal search of parameters. But I guess you mean that it doesn't perform a tree search? Quoting from the abstract of the paper on arxiv [1]: In this work we present the MuZero algorithm which, by combining _a tree-based search_ with a learned model, achieves superhuman performance in a range of challenging and visually complex domains, withoutany knowledge of their underlying dynamics. (My underlining) If I remember correctly, MuZero is model-free in the sense that it learns its own evaluation function and reward policy etc (also going by the abstract). But it retains MCTS. Indeed, it wouldn't really make sense to drop MCTS from the architecture of a system designed to play games. I mean, it would be really hard to justify discarding a component that is well known to work and work well, both from an engineering and a scientific point of view. _________________ https://arxiv.org/abs/1911.08265 https://arxiv.org/abs/1911.08265
  - gwern 6y ago
    MuZero doesn't do a search over explicit board states, MCTS (where are the playouts at the leaf nodes? where is the simulator state?) or otherwise: it does search over internal-abstract-reward-predictive-states/action pairs, much like a human does, who thinks through possible actions using an internal representation sometimes backtracking as they decide a move is bad and evaluating a different one which feels better. It's search over a tree of possible actions, sure, but this is not MCTS, even if they loosely use the phrase in places (similarly, the tree search Zero does for gameplay is not MCTS, even if people sometimes describe it that way or conflate it with the training).
    - YeGoblynQueenne 6y ago
      I'm a bit confused. MuZero doesn't do a "formal search" (as per your previous comment) but it does a tree search (as per your current comment). It doesn't perform MCTS, even though the paper itself states it performs MCTS. I quote from the arxiv paper again: Appendix B Search We now describe the search algorithm used by MuZero. Our approach is based upon Monte-Carlo tree search with upper confidence bounds, an approach to planning that converges asymptotically to the optimal policy in single agent domains and to the minimax value function in zero sum games [22]. So I'm sorry but I really don't understand what you mean here. Also, as discussed in other comments, it's dangerous to assume anyhing about how "a human does" anything to do with any kind of mental calculation. Whatever MuZero does and however good or bad it does it, there is nothing to tell us that it does it as a human does.
- YeGoblynQueenne 6y ago
  >> (This is not the first time I've been puzzled by their pessimism on HN.) I don't understand why you keep making personal comments like that about me. I suspect you don't realise that they are unpleasant. Please let me make it clear: such personal comments are unpleasant. Could you please stop them? Thank you.
YeGoblynQueenne 6y ago
>> Are we certain that well-trained human players are not doing search? Yes- because human players can only search a tiny portion of a game tree and a minimax search of the same extent is not even sufficient to beat a dedicated human in tic-tac-to, leta lone chess. That is, unless one wishes to countenance the possibility of an "unconscious search" which of course might as well be "the grace of God" or any such hand-wavy non-explanation. >> It's possible that a search subnetwork gets "compiled without debugger symbols" and the owner of the brain is simply unaware that it's happening. Sorry, I don't understand what you mean.
- oezi 6y ago
  Why do you dismiss the unconscious search that humans do in Go? Having learned Go some years ago it is such an exciting thing to realize that with practice the painstaking process of consciously evaluating the myriads possibilities of moves gives way to just "seeing" solutions out of nothing. You can really feel that your brain did wire itself up to do analysis for you at a level that is subconscious but interfaces so gracefully with your conscious cognition that it is a real marvel.
  - YeGoblynQueenne 6y ago
    >> Why do you dismiss the unconscious search that humans do in Go? The question is why you say that humans perform an unconscious search when they play Go. And what kind of search is it, other than unconscious? Could you describe it, e.g. in algorithmic notation? I mean, I'm sure you couldn't because if you could then the problem of teaching a computer to play Go as well as a human would have been solved years and years ago. But, if you can't describe what you're doing, then how do you know it's a "search"? Note that in AI, when we talk of "search" (edit: at least, in the context of game-playing) we mean something very specific: an algorithm that examines the nodes of a tree and applies some criterion to label each examined node as a target node or not a target node. Humans are absolutely awful at executing such an algorithm with our minds for any but the most trivial of trees, at least compared to computers.
    - 6y ago
bsder 6y ago
> Are we certain that well-trained human players are not doing search? Some, but there's a LOT more context pruning the search space. Watch some of the chess grandmasters play and miss obvious winning moves. Why? "Well, I didn't bother looking at that because <insert famous grandmaster> doesn't just hang a rook randomly."

gwern 6y ago

I'm not sure why YeGoblynQueenne thinks this is such a mystery. (This is not the first time I've been puzzled by their pessimism on HN.) There is no mystery here: AlphaZero shows that you can get superhuman performance by searching only a few ply by sufficiently good pattern recognition in a highly parameterized and well-trained value function, and MuZero makes this point even more emphatically by doing away with the formal search entirely in favor of an more abstract recurrent pondering. What more is there to say?

YeGoblynQueenne 6y ago
MuZero performs a "formal search". In many more ways than one, for example optimisation is still a search for an optimal search of parameters. But I guess you mean that it doesn't perform a tree search? Quoting from the abstract of the paper on arxiv [1]: In this work we present the MuZero algorithm which, by combining _a tree-based search_ with a learned model, achieves superhuman performance in a range of challenging and visually complex domains, withoutany knowledge of their underlying dynamics. (My underlining) If I remember correctly, MuZero is model-free in the sense that it learns its own evaluation function and reward policy etc (also going by the abstract). But it retains MCTS. Indeed, it wouldn't really make sense to drop MCTS from the architecture of a system designed to play games. I mean, it would be really hard to justify discarding a component that is well known to work and work well, both from an engineering and a scientific point of view. _________________ https://arxiv.org/abs/1911.08265 https://arxiv.org/abs/1911.08265
- gwern 6y ago
  MuZero doesn't do a search over explicit board states, MCTS (where are the playouts at the leaf nodes? where is the simulator state?) or otherwise: it does search over internal-abstract-reward-predictive-states/action pairs, much like a human does, who thinks through possible actions using an internal representation sometimes backtracking as they decide a move is bad and evaluating a different one which feels better. It's search over a tree of possible actions, sure, but this is not MCTS, even if they loosely use the phrase in places (similarly, the tree search Zero does for gameplay is not MCTS, even if people sometimes describe it that way or conflate it with the training).
  - YeGoblynQueenne 6y ago
    I'm a bit confused. MuZero doesn't do a "formal search" (as per your previous comment) but it does a tree search (as per your current comment). It doesn't perform MCTS, even though the paper itself states it performs MCTS. I quote from the arxiv paper again: Appendix B Search We now describe the search algorithm used by MuZero. Our approach is based upon Monte-Carlo tree search with upper confidence bounds, an approach to planning that converges asymptotically to the optimal policy in single agent domains and to the minimax value function in zero sum games [22]. So I'm sorry but I really don't understand what you mean here. Also, as discussed in other comments, it's dangerous to assume anyhing about how "a human does" anything to do with any kind of mental calculation. Whatever MuZero does and however good or bad it does it, there is nothing to tell us that it does it as a human does.
YeGoblynQueenne 6y ago
>> (This is not the first time I've been puzzled by their pessimism on HN.) I don't understand why you keep making personal comments like that about me. I suspect you don't realise that they are unpleasant. Please let me make it clear: such personal comments are unpleasant. Could you please stop them? Thank you.

YeGoblynQueenne 6y ago

>> Are we certain that well-trained human players are not doing search? Yes- because human players can only search a tiny portion of a game tree and a minimax search of the same extent is not even sufficient to beat a dedicated human in tic-tac-to, leta lone chess. That is, unless one wishes to countenance the possibility of an "unconscious search" which of course might as well be "the grace of God" or any such hand-wavy non-explanation. >> It's possible that a search subnetwork gets "compiled without debugger symbols" and the owner of the brain is simply unaware that it's happening. Sorry, I don't understand what you mean.

oezi 6y ago
Why do you dismiss the unconscious search that humans do in Go? Having learned Go some years ago it is such an exciting thing to realize that with practice the painstaking process of consciously evaluating the myriads possibilities of moves gives way to just "seeing" solutions out of nothing. You can really feel that your brain did wire itself up to do analysis for you at a level that is subconscious but interfaces so gracefully with your conscious cognition that it is a real marvel.
- YeGoblynQueenne 6y ago
  >> Why do you dismiss the unconscious search that humans do in Go? The question is why you say that humans perform an unconscious search when they play Go. And what kind of search is it, other than unconscious? Could you describe it, e.g. in algorithmic notation? I mean, I'm sure you couldn't because if you could then the problem of teaching a computer to play Go as well as a human would have been solved years and years ago. But, if you can't describe what you're doing, then how do you know it's a "search"? Note that in AI, when we talk of "search" (edit: at least, in the context of game-playing) we mean something very specific: an algorithm that examines the nodes of a tree and applies some criterion to label each examined node as a target node or not a target node. Humans are absolutely awful at executing such an algorithm with our minds for any but the most trivial of trees, at least compared to computers.
  - 6y ago

bsder 6y ago

> Are we certain that well-trained human players are not doing search? Some, but there's a LOT more context pruning the search space. Watch some of the chess grandmasters play and miss obvious winning moves. Why? "Well, I didn't bother looking at that because <insert famous grandmaster> doesn't just hang a rook randomly."