190 lines
5.2 KiB
Plaintext
190 lines
5.2 KiB
Plaintext
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Some remarks concerning the files collected:
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seki1.sgf
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The "classical" seki. gnugo plays correctly, but the score is wrong.
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seki2.sgf
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Each side has an eye
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seki3.sgf
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Another one.
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seki_stupid.sgf
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Here i wanted to see, if gnugo plays the stupid move C 1. Well it doesnt.
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But maybe it is good to keep the file, just to make sure that future
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"improvements" dont spoil it.
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sekichallenge.sgf
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Thats what it is. gnugo makes mistakes and loses everything. But i get
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the impression that the reading depth is just a little bit too short.
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seki_score.sgf
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a seki. unless i counted it wrongly, assuming an equal number of
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prisoners
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the japanese rules give:
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territory b 96 w 97
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prisoners b 0 w 0
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seki b 0 w 0
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the chinese rules give:
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territory b 96 w 97
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stones b 79 w 79
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seki b 8.5 w 1.5
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so there is a difference of 7 points, depending on which rules you take.
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twoko_seki1.sgf
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A double ko seki. with the present program and playing japanese rules
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the eternal loop can only be avoided, if both players have enough
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intelligence to see that it is impossible to win. i said already
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before that i think that the program is wrong. that is after two
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passes, i thought the game is finished, but do_pass allows gnugo
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to play another move, so the loop continues. if we change do_pass,
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it would be good enough to have one intelligent player to avoid
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the loop. Since we know nothing about the intelligence of our
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opponent, the intelligent player would have to be gnugo.
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So if we stick to japanese rules, this needs a detailed analysis
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of the situation.
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In principle the japanese rules define in their precedents
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that this position is seki, should gnugo know the precedents ?
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chinese rules avoid the loop and give the interesting result, that
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whoever insists on playing, loses everything. maybe not everybody
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knows that already by heart, so it goes like this:
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w takes ko 1
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b takes ko 2
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w tenuki
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b takes ko 1
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w takes ko 2
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b tenuki
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finally there will be no playable point left on the board.
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lets assume that b has played the last possible move.
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then if w insists:
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w takes ko 1
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b takes ko 2
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w passes
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b takes ko 1
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now w would like to take ko 2, but that is forbidden, because it
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reproduces a position, which has already existed before.
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so
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w passes
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b takes all.
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If there is another ko somewhere else on the board, then this
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double ko would be an example of what Ing calls a disturbing ko.
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twoko_seki2.sgf
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Another double ko seki. twoko_seki1 has two groups with an eye each,
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this one has one liberty common to both groups.
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twoko_live.sgf
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B is alive.
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twoko_dead.sgf
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W is dead.
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fourko.sgf
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A quadruple ko. I have never heard about that, but i guess the
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japanese will have to cancel the game. with chinese rules one
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can play it of course, but it is rather tricky.
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onadare_ko.sgf
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The double ko variation of the onadare joseki.
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onadare_ko2.sgf
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Here i have added a ko in the lower right corner. This is completely
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different from twoko_seki1.sgf plus another ko. here the black group
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in the double ko is alive. however white has an unlimited supply
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of ko threats, so it will win any other ko. If i understand this
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correctly, the japanese do not consider this to be a triple ko
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I thought that Ing should call the double ko a "fighting ko",
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but apparently he doesnt. So the Ing rules would have to treat
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the two cases twoko_seki1.sgf plus another ko and the present one
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the same way.
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gnugo does not know how to handle this.
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bent4.sgf
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gnugo handles this correctly. when i said maybe for the wrong reasons
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Gunnar said, what do i mean. well first one should look, if it does
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all possible variations correctly. But what i really was afraid of, was
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maybe it treats it the same way it handles seki. only for seki it is
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wrong and here it is right. anyway, whenever the seki has been fixed,
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one should look, if this is still ok.
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bent4_2.sgf
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Another one. This one is also handled correctly.
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seki_bent4.sgf
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The combination of a bent4 with a seki, which gives an unremovable
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ko threat. The japanese rules kill the bent4 anyway. gnugo has
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various difficulties.
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doublebent4.sgf
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I guess the japanese rules say that both groups are dead ???
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Apart from that gnugo handles it correctly.
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threeko1.sgf
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The "classical" triple ko. i guess, if we play japanese rules,
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gnugo should realise that the game should be cancelled.
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Playing chinese rules one can usually neutralise two ko's
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and then play the one which is remaining as before.
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threeko2.sgf
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This is a fake. white can never win this.
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threeko3.sgf
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Similar to threeko2.sgf, with a slight difference. If it is
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white's turn it can play B 5 and then it becomes a double ko
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which black cannot win.
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If it is black's turn, the japanese will cancel the game and
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for the chinese white can never win.
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chosei.sgf
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A chosei( long life / eternal life ).
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Apart from the fact that the game should be cancelled,
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gnugo makes a lot of mistakes and loses everything.
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It seems everybody who writes about that, shows the same diagram.
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Maybe this is the only one ?
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If people think that this is interesting, I would have to do
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some work.
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junkan-ko.sgf
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A junkan-ko (round robin ko). Everything I wrote about chosei
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is valid here as well. i thought a little about these positions,
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but i dont want to bore everybody, unless somebody really wants
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to hear about it.
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