We've probably beat this horse to death, but here's David Silver (lead programmer at top of alphago paper): "The search process itself is not based on brute force, more on something akin to imagination…. "
On Aug 6, 2017 4:08 PM, "Brian Sheppard" <sheppar...@aol.com> wrote: Possibly you are answering a different question than the one posed? Possibly your interpretation is the one actually intended. I don’t know, and maybe you could be right about what was being asked. I do know the semantics of brute force, though, which you quoted below. Note that “brute force” != unintelligent. Inevitably, every brute force algorithm will incorporate intelligent heuristics. Consider the evolution of minimax, for example, via alpha-beta, selective extensions, LMR, etc. *From:* Steven Clark [mailto:steven.p.cl...@gmail.com] *Sent:* Sunday, August 6, 2017 2:52 PM *To:* Brian Sheppard <sheppar...@aol.com> *Cc:* computer-go <computer-go@computer-go.org> *Subject:* Re: [Computer-go] Alphago and solving Go This is semantics. Yes, in the limit of infinite time, it is brute-force. Meanwhile, in the real world, AlphaGo chooses to balance its finite time budget between depth & width. The mere fact that the CNN policy network generates a score for each coordinate on the board in a given position, does not mean that all of those nodes will be expanded in any reasonable scenario. On Sun, Aug 6, 2017 at 2:20 PM, Brian Sheppard <sheppar...@aol.com> wrote: I understand why most people are saying that AlphaGo is not brute force, because it appears to be highly selective. But MCTS is a full width search. Read the AlphaGo papers, as one of the other respondents (rather sarcastically) suggested: AlphaGo will eventually search every move at every node. MCTS has the appearance of a selective search because time control terminates search while the tree is still ragged. In fact, it will search every continuation an infinite number of times. In order to have high performance, an MCTS implementation needs to search best moves as early as possible in each node. It is in this respect that AlphaGo truly excels. (AlphaGo also excels at whole board evaluation, but that is a separate topic.) *From:* Steven Clark [mailto:steven.p.cl...@gmail.com] *Sent:* Sunday, August 6, 2017 1:14 PM *To:* Brian Sheppard <sheppar...@aol.com>; computer-go < computer-go@computer-go.org> *Subject:* Re: [Computer-go] Alphago and solving Go Why do you say AlphaGo is brute-force? Brute force is defined as: "In computer science, brute-force search or exhaustive search, also known as generate and test, is a very general problem-solving technique that consists of *systematically enumerating all possible candidates* for the solution and checking whether each candidate satisfies the problem's statement." The whole point of the policy network is to avoid brute-force search, by reducing the branching factor... On Sun, Aug 6, 2017 at 10:42 AM, Brian Sheppard via Computer-go < computer-go@computer-go.org> wrote: Yes, AlphaGo is brute force. No it is impossible to solve Go. Perfect play looks a lot like AlphaGo in that you would not be able to tell the difference. But I think that AlphaGo still has 0% win rate against perfect play. My own best guess is that top humans make about 12 errors per game. This is estimated based on the win rate of top pros in head-to-head games. The calculation starts by assuming that Go is a win at 6.5 komi for either Black (more likely) or White, so a perfect player would win 100% for Black. Actual championship caliber players win 51% to 52% for Black. In 9-dan play overall, I think the rate is 53% to 54% for Black. Then you can estimate how many errors each player has to make to bring about such a result. E.g., If players made only one error on average, then Black would win the vast majority of games, so they must make more errors. I came up with 12 errors per game, but you can reasonably get other numbers based on your model. Best, Brian *From:* Computer-go [mailto:computer-go-boun...@computer-go.org] *On Behalf Of *Cai Gengyang *Sent:* Sunday, August 6, 2017 9:49 AM *To:* computer-go@computer-go.org *Subject:* [Computer-go] Alphago and solving Go Is Alphago brute force search? Is it possible to solve Go for 19x19 ? And what does perfect play in Go look like? How far are current top pros from perfect play? Gengyang _______________________________________________ Computer-go mailing list Computer-go@computer-go.org http://computer-go.org/mailman/listinfo/computer-go
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