[computer-go] MC hard positions for MCTS

2009-10-27 Thread Petri Pitkanen
Hello, Are there more peculiar situation that will cause problems for MCTS apart from the three I know. 1. Nakade (this is partuially solved in most of the programs) 2. Semeais 3. Double Ko. Last one was new to me. See http://files.gokgs.com/games/2009/10/26/ManyFaces-Hyoga.sgf In that game

Re: [computer-go] MC hard positions for MCTS

2009-10-27 Thread Stefan Kaitschick
to be safe. Stefan - Original Message - From: Petri Pitkanen To: computer-go Sent: Tuesday, October 27, 2009 11:05 AM Subject: [computer-go] MC hard positions for MCTS Hello, Are there more peculiar situation that will cause problems for MCTS apart from the three I

Re: [computer-go] MC hard positions for MCTS

2009-10-27 Thread Darren Cook
But the biggest problem is that the path to life/ko is very narrow. The defender has many useful moves and the invader has few. So MCTS will falsely judge invadable areas to be safe. Interesting, I'd not thought about it in that respect: I know I can soon find positions where the defender has

Re: [computer-go] MC hard positions for MCTS

2009-10-27 Thread Petri Pitkanen
That is well known fact of go, that usually defence is easier. But evidence is anecdotal. Getting real evidence from real games cannot be automated as all concept involved are rather vague and difficult to classify. Hence I am willing to accept such information as passed on to me in books like

Re: [computer-go] MC hard positions for MCTS

2009-10-27 Thread Stefan Kaitschick
But, has anyone gathered stats on positions, from real games, that require precise play by the defender/attacker/both/neither? Is defending really easier than attacking? Darren Who is the defender? One side is defending his territory, the other side is defending his group. I think the

Re: [computer-go] MC hard positions for MCTS

2009-10-27 Thread Stefan Kaitschick
This causes what I call the horizon effect which prevents the tree exploration to work properly - the moment the tree finds a sequence that unbiases the simulations, it is horrified by the bad results [*] and switches to a different branch, until it finds the same; thus, the bot pushes the

RE: [computer-go] MC hard positions for MCTS

2009-10-27 Thread David Fotland
Don’t forget about ladders. Many programs have special code to avoid playing in losing ladders. From: computer-go-boun...@computer-go.org [mailto:computer-go-boun...@computer-go.org] On Behalf Of Petri Pitkanen Sent: Tuesday, October 27, 2009 3:06 AM To: computer-go Subject: [computer-go] MC

Re: [computer-go] MC hard positions for MCTS

2009-10-27 Thread Petr Baudis
On Tue, Oct 27, 2009 at 01:10:09PM +0100, Stefan Kaitschick wrote: But, has anyone gathered stats on positions, from real games, that require precise play by the defender/attacker/both/neither? Is defending really easier than attacking? Darren Who is the defender? One side is