Gérard TAILLE wrote:
Though I now understand the meaning of the three marked stones I did not manage to find a white move better than the marked white stone in the diagram above. Does such white move really exist?
There are 6 such moves
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| Subtilities for ko threats handling http://www.lifein19x19.com/viewtopic.php?f=12&t=18572 |
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| Author: | dany [ Thu Jan 20, 2022 6:06 pm ] |
| Post subject: | Re: Subtilities for ko threats handling |
Gérard TAILLE wrote: Though I now understand the meaning of the three marked stones I did not manage to find a white move better than the marked white stone in the diagram above. Does such white move really exist? There are 6 such moves
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| Author: | Gérard TAILLE [ Fri Jan 21, 2022 4:24 am ] |
| Post subject: | Re: Subtilities for ko threats handling |
dany wrote: Gérard TAILLE wrote: Though I now understand the meaning of the three marked stones I did not manage to find a white move better than the marked white stone in the diagram above. Does such white move really exist? There are 6 such moves Maybe we are in line but it seems we discuss on two different positions. I considered only the following position resulting from Ichiriki problem, I mean with no black stone on J8. In this position do you agree that the white marked is the only best move? Do you agree also that the presence of the three marked stones is essential in order to say that the white marked stone is really the only best move? |
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| Author: | dany [ Fri Jan 21, 2022 4:46 am ] |
| Post subject: | Re: Subtilities for ko threats handling |
Gérard TAILLE wrote: dany wrote: Gérard TAILLE wrote: Though I now understand the meaning of the three marked stones I did not manage to find a white move better than the marked white stone in the diagram above. Does such white move really exist? There are 6 such moves Maybe we are in line but it seems we discuss on two different positions. I considered only the following position resulting from Ichiriki problem, I mean with no black stone on J8. In this position do you agree that the white marked is the only best move? Do you agree also that the presence of the three marked stones is essential in order to say that the white marked stone is really the only best move? Yes.Yes |
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| Author: | dany [ Fri Jan 21, 2022 4:58 am ] |
| Post subject: | Re: Subtilities for ko threats handling |
The original position and my modification are the same story, the same variations. The only difference is which variation you prefer as a solution. Ichiriki prefers the eternal life variation. I prefers another variation. original position: Ichiriki variation - the best another variation modified position: Ichiriki variation another variation - the best |
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| Author: | Cassandra [ Fri Jan 21, 2022 6:28 am ] |
| Post subject: | Re: Subtilities for ko threats handling |
dany wrote: The original position and my modification are the same story, the same variations. Did you adjust the komi while adding a Black stone to the board? Or did you suppose that the added Black stone has captured a White one? |
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| Author: | Gérard TAILLE [ Fri Jan 21, 2022 6:35 am ] |
| Post subject: | Re: Subtilities for ko threats handling |
dany wrote: The original position and my modification are the same story, the same variations. The only difference is which variation you prefer as a solution. Ichiriki prefers the eternal life variation. I prefers another variation. original position: Ichiriki variation - the best another variation modified position: Ichiriki variation another variation - the best I understand Dany and I agree with your results. As far as I am concerned I do not like very much Eternal Life and I prefer using area scoring and superko. Here I have to recognize that in the context of japanese rules the original position is very well built. Beside the threat handling difficulty the result is quite interesting : as soon as a player try to avoid the eternal life then this player will lose by half a point. Ther modified position avoid the Eternal life but then the result is far less interesting because white can win in several variations. |
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| Author: | dany [ Fri Jan 21, 2022 7:45 am ] |
| Post subject: | Re: Subtilities for ko threats handling |
Gérard TAILLE wrote: Ther modified position avoid the Eternal life but then the result is far less interesting because white can win in several variations. No. White can win in the only variation |
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| Author: | dany [ Fri Jan 21, 2022 8:13 am ] |
| Post subject: | Re: Subtilities for ko threats handling |
In the original position, the interesting variation remains hidden behind Ichiriki solution. I do not like it. In the modified position the interesting variation becomes a solution and Ichiriki solution becomes a strong false idea)) |
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| Author: | dany [ Fri Jan 21, 2022 8:41 am ] |
| Post subject: | Re: Subtilities for ko threats handling |
Cassandra wrote: dany wrote: The original position and my modification are the same story, the same variations. Did you adjust the komi while adding a Black stone to the board? Or did you suppose that the added Black stone has captured a White one? I reduced black's score by 1 point |
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| Author: | Gérard TAILLE [ Fri Jan 21, 2022 9:15 am ] |
| Post subject: | Re: Subtilities for ko threats handling |
dany wrote: In the original position, the interesting variation remains hidden behind Ichiriki solution. I do not like it. In the modified position the interesting variation becomes a solution and Ichiriki solution becomes a strong false idea)) Yes Dany I agree with you but I still do not see how black has to play in order that all white moves are forced (no variation). As an example in the following position: white can choose between several moves can't she? |
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| Author: | dany [ Fri Jan 21, 2022 9:55 am ] |
| Post subject: | Re: Subtilities for ko threats handling |
Gérard TAILLE wrote: dany wrote: In the original position, the interesting variation remains hidden behind Ichiriki solution. I do not like it. In the modified position the interesting variation becomes a solution and Ichiriki solution becomes a strong false idea)) Yes Dany I agree with you but I still do not see how black has to play in order that all white moves are forced (no variation). As an example in the following position: white can choose between several moves can't she? Yes, different moves (or different moves order). But for me it's all the same variant - black kill white's stones and white save H6 |
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| Author: | Gérard TAILLE [ Fri Jan 21, 2022 10:39 am ] |
| Post subject: | Re: Subtilities for ko threats handling |
dany wrote: Gérard TAILLE wrote: dany wrote: In the original position, the interesting variation remains hidden behind Ichiriki solution. I do not like it. In the modified position the interesting variation becomes a solution and Ichiriki solution becomes a strong false idea)) Yes Dany I agree with you but I still do not see how black has to play in order that all white moves are forced (no variation). As an example in the following position: white can choose between several moves can't she? Yes, different moves (or different moves order). But for me it's all the same variant - black kill white's stones and white save H6 BTW I think the area in the bottom left corner was not handled correctly for a strict local point of view (no impact for the Ichiriki problem) white can create another threat by to reach the following position which is a pass-alive position Instead it seems technically strictly better for white to play white can still create another threat by to reach the following position which is NOT a pass-alive position |
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| Author: | Gérard TAILLE [ Fri Jan 21, 2022 11:07 am ] |
| Post subject: | Re: Subtilities for ko threats handling |
dany wrote: Gérard TAILLE wrote: dany wrote: In the original position, the interesting variation remains hidden behind Ichiriki solution. I do not like it. In the modified position the interesting variation becomes a solution and Ichiriki solution becomes a strong false idea)) Yes Dany I agree with you but I still do not see how black has to play in order that all white moves are forced (no variation). As an example in the following position: white can choose between several moves can't she? Yes, different moves (or different moves order). But for me it's all the same variant - black kill white's stones and white save H6 For the black moves it is worse: In original Ichiriki problem  is the best move.With the modified position it seems black can still reach the best result by beginning with "a" instead of in the diagram above.
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| Author: | dany [ Fri Jan 21, 2022 11:35 am ] |
| Post subject: | Re: Subtilities for ko threats handling |
Gérard TAILLE wrote: For the black moves it is worse: In original Ichiriki problem is the best move.With the modified position it seems black can still reach the best result by beginning with "a" instead of in the diagram above.I do not think so |
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| Author: | Gérard TAILLE [ Fri Jan 21, 2022 11:53 am ] |
| Post subject: | Re: Subtilities for ko threats handling |
dany wrote: Gérard TAILLE wrote: For the black moves it is worse: In original Ichiriki problem is the best move.With the modified position it seems black can still reach the best result by beginning with "a" instead of in the diagram above.I do not think so OK, let's try and if I am not wrong black reaches her best result (white wins by 0.5 point). |
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| Author: | dany [ Fri Jan 21, 2022 1:28 pm ] |
| Post subject: | Re: Subtilities for ko threats handling |
W+1.5 |
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| Author: | Gérard TAILLE [ Fri Jan 21, 2022 3:01 pm ] |
| Post subject: | Re: Subtilities for ko threats handling |
dany wrote: W+1.5 Oops sorry Dany, you are right. Finally, with the modified position the only weakness is when the position above is reached. From that point both players may have several choices beginning with black who can play a, b, c or d. |
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| Author: | dany [ Fri Jan 21, 2022 4:19 pm ] |
| Post subject: | Re: Subtilities for ko threats handling |
Gérard TAILLE wrote: dany wrote: W+1.5 Oops sorry Dany, you are right. Finally, with the modified position the only weakness is when the position above is reached. From that point both players may have several choices beginning with black who can play a, b, c or d. No choices. The only road (black can play 1,3,5 in any order) |
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| Author: | Gérard TAILLE [ Sat Jan 22, 2022 4:31 am ] |
| Post subject: | Re: Subtilities for ko threats handling |
dany wrote: Gérard TAILLE wrote: dany wrote: W+1.5 Oops sorry Dany, you are right. Finally, with the modified position the only weakness is when the position above is reached. From that point both players may have several choices beginning with black who can play a, b, c or d. No choices. The only road (black can play 1,3,5 in any order) Again it is right Dany The sequence above cannot be an alternative because white has a ko threat available at "a". Not that obvious is it? |
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| Author: | dany [ Sat Jan 22, 2022 7:16 am ] |
| Post subject: | Re: Subtilities for ko threats handling |
Yes, "a" prevent black 5 |
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