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 Post subject: Re: Thermography #121 Posted: Wed Oct 14, 2020 8:08 am
 Lives with ko

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Bill Spight wrote:
Gérard TAILLE wrote:
OK Bill, now I see clearly what is your calculation and due to a miscalculation my example is not the one I would have taken.
Instead of the sequence 6 + 4 + 5 + 3 + 2 + 4 can we take the simplier sequence 6 + 4 + 5 + 6 + 2
and the question is : at what temperature will white blocks the corridor by playing at "a"?
This time I found t=5 but I am not sure at 100% of such result

Let's see.

{0|-2||-8|||-13||||-17|||||-23}

Above temperature 1 we have

{-1|-8||-13|||-17||||-23}

Above temperature 3½ we have

{-4½|-13||-17|||-23}

Above temperature 4¼ we have

{-8¾|-17||-23}

Above temperature 4⅛ we might have

{-12⅞|-23} but 4⅛ < 4¼ so above temperature 4 we have

{-13|-23}

Above temperature 5 we have

-18.

The thermograph is this.

Attachment:
The attachment GTG.png is no longer available

First of all we note the calculation giving the sequence
0, -1, -4½, -8¾, -12⅞
then handling the possibility to create a sente situation you made the correction
-12⅞ -> 13
and then the sequence ended by
13, 18
in order to give the correct thermograph.

From a theoritical point of view your method to reach the thermograph is correct but I see two major drawbacks for pratice:
1) The sequence 0, -1, -4½, -8¾, -12⅞, 13, 18 is a very poor sequence in terms of convergence towards the final value, because the most significant change through this sequence appears at the end of the sequence and not at the beginning
2) When you look in details to the correction -12⅞ -> 13 you discover that a part of the calculation to build the sequence 0, -1, -4½, -8¾, -12⅞ may be not necessary

With this in mind I look for another procedure for building this thermograph. Here it is.

Firstly we can note that for such corridor the thermograph looks like the following
Attachment:

corridor.png [ 5.09 KiB | Viewed 512 times ]

Let's take again the corridor defined by the sequence 6, 4, 5, 6, 2

The first figure of the sequence (6 in the example) is the most important figure and this figure is the width of the thermograph base.
In order to draw the correct thermograph we have only to calculate the value x shown above in the attachement file.
My goal is to calculate this value x by following the sequence in the most efficient order and by handling at each step a min value and a max value for x.

Taking the first value of the sequence (6) I initialise
min = 0 and max = 6

Now I get to each figure in the sequence a weight designing the influence of the figure on the final result
The first figure (6) has the weight 1
The second figure (4) has the weight 1/2
The third figure (5) has the weight 1/4
The fourth figure (6) has the weight 1/8
The fifth figure (2) has the weight 1/16

Now let's procede:

Let's take the second figure (4), I handle the contribution of this figure to find x as follows:
The weight of this figure being 1/2 the second figure 4 can only increase the min value by figure between 2 and 4. The new min-max value are then
min = 2 max = 4

Let's take the third figure (5)
The weight of this figure being 1/4 this third figure 5 can only increase the min value by figure between 1¼ and 2½. The new min-max value are then
min = 3¼ max = 4
Note that the max value as not changed because previous_min + 2½ = 2 + 2½ = 4½ > previous_max

Let's take the fourth figure (6)
The weight of this figure being 1/8 the fourth figure 6 can only increase the min value by figure between ¾ and 1½. The new min max value are then
min = 4 max = 4

Because min = max = 4 you stop there and draw the thermograph accordingly without looking to the remaining figures defining the corridor!

BTW, if you are a little lazy and you look only on a good estimation of the thermograph you can of course stop for example after the third figure. Here you have min = 3¼ max = 4 and you may use your feeling to estimate x between 3¼ and 4. Seeing the following figure 6, which is quite high your feeling will certainly choose a value very near from the correct value 4 !

 This post by Gérard TAILLE was liked by: Bill Spight
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 Post subject: Re: Thermography #122 Posted: Wed Oct 14, 2020 12:08 pm
 Honinbo

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Gérard TAILLE wrote:
Bill Spight wrote:
Gérard TAILLE wrote:
OK Bill, now I see clearly what is your calculation and due to a miscalculation my example is not the one I would have taken.
Instead of the sequence 6 + 4 + 5 + 3 + 2 + 4 can we take the simplier sequence 6 + 4 + 5 + 6 + 2
and the question is : at what temperature will white blocks the corridor by playing at "a"?
This time I found t=5 but I am not sure at 100% of such result

Let's see.

{0 | -2 || -8 ||| -13 |||| -17 ||||| -23}

Above temperature 1 we have

{-1 | -8 || -13 ||| -17 |||| -23}

Above temperature 3½ we have

{-4½ | -13 || -17 ||| -23}

Above temperature 4¼ we have

{-8¾ | -17 || -23}

Above temperature 4⅛ we might have

{-12⅞ | -23} but 4⅛ < 4¼ so above temperature 4 we have

{-13 | -23}

Above temperature 5 we have

-18.

The thermograph is this.

Attachment:
GTG.png

First of all we note the calculation giving the sequence
0, -1, -4½, -8¾, -12⅞
then handling the possibility to create a sente situation you made the correction
-12⅞ -> 13
and then the sequence ended by
13, 18
in order to give the correct thermograph.

From a theoritical point of view your method to reach the thermograph is correct but I see two major drawbacks for pratice:
1) The sequence 0, -1, -4½, -8¾, -12⅞, 13, 18 is a very poor sequence in terms of convergence towards the final value, because the most significant change through this sequence appears at the end of the sequence and not at the beginning
2) When you look in details to the correction -12⅞ -> 13 you discover that a part of the calculation to build the sequence 0, -1, -4½, -8¾, -12⅞ may be not necessary

Good points. Note that this is not a thermographic technique. It is one that a player might use at the table. Yours is a thermographic technique.

Quote:
With this in mind I look for another procedure for building this thermograph. Here it is.

Firstly we can note that for such corridor the thermograph looks like the following
Attachment:
corridor.png

Let's take again the corridor defined by the sequence 6, 4, 5, 6, 2

The first figure of the sequence (6 in the example) is the most important figure and this figure is the width of the thermograph base.
In order to draw the correct thermograph we have only to calculate the value x shown above in the attachement file.
My goal is to calculate this value x by following the sequence in the most efficient order and by handling at each step a min value and a max value for x.

Taking the first value of the sequence (6) I initialise
min = 0 and max = 6

That, I believe, is equivalent to finding the minimum and maximum values for the game {z|-17||-23}, where z ≥ -17. When z = -17 we get the minimum of 0, and when z ≥ -5 we get the maximum of 6. OC, we know that the maximum for z in this corridor is 0.

Quote:
Now I get to each figure in the sequence a weight designing the influence of the figure on the final result
The first figure (6) has the weight 1
The second figure (4) has the weight 1/2
The third figure (5) has the weight 1/4
The fourth figure (6) has the weight 1/8
The fifth figure (2) has the weight 1/16

Now let's procede:

Let's take the second figure (4), I handle the contribution of this figure to find x as follows:
The weight of this figure being 1/2 the second figure 4 can only increase the min value by figure between 2 and 4. The new min-max value are then
min = 2 max = 4

For the game {-13 | -13 || -17 ||| -23} we get the minimum of 2. For the game {0 | -13 || -17 ||| -23} we get the maximum of 4. (OC, we could use Big instead of 0 and not calculate the mean of -13 and 0.)

Quote:
Let's take the third figure (5)
The weight of this figure being 1/4 this third figure 5 can only increase the min value by figure between 1¼ and 2½. The new min-max value are then
min = 3¼ max = 4
Note that the max value as not changed because previous_min + 2½ = 2 + 2½ = 4½ > previous_max

For the game {-8 | -8 || -13 ||| -17 |||| -23} we get the minimum of 3¼. For the game {0 | -8 || -13 ||| -17 |||| -23} we get the maximum of 4, because {0 | -8 || -13 ||| -17} is a Black sente.

Quote:
Let's take the fourth figure (6)
The weight of this figure being 1/8 the fourth figure 6 can only increase the min value by figure between ¾ and 1½. The new min max value are then
min = 4 max = 4

For the game {-2 | -2 || -8 ||| -13 |||| -17 ||||| -23} we get the minimum of 4, because {-2 | -2 || -8 ||| -13 |||| -17} is ambiguous between sente and gote. We do not have to check {0 | -2 || -8 ||| -13 |||| -17}, as it will be a Black sente.

Quote:
Because min = max = 4 you stop there and draw the thermograph accordingly without looking to the remaining figures defining the corridor!

BTW, if you are a little lazy and you look only on a good estimation of the thermograph you can of course stop for example after the third figure. Here you have min = 3¼ max = 4 and you may use your feeling to estimate x between 3¼ and 4. Seeing the following figure 6, which is quite high your feeling will certainly choose a value very near from the correct value 4 !

The method that I used, starting from the left, assumes that each game is gote unless we find that it is sente. This is the non-thermographic method that I usually teach, because it seems that people understand it fairly quickly. Also, on the go board gote are more common than sente. You can also use the method of assuming that each game is sente unless we find that it is gote. That also works. In practice, we can also guess which it is and proceed until and unless proven wrong.

Let's apply the sente first method to this corridor, assuming that each step into the corridor is sente.

{Big | -17 || -23} count = -17 gain = 6

{Big | -13 || -17 ||| -23} count = -18 gain = 5

{Big | -8 || -13 ||| -17 |||| -23} count = -18 gain = 5

(We can infer this from your sequence, 6 + 4 + 5 + 6 + 2, because 5 > 4. This is obvious from the thermograph.)

This is consistent with {Z | -13 || -17} being sente, where Z ≥ -13, but we have failed to disprove it. Let's try to do so by substituting the next value in the corridor for Big in {Big | -8}.

{-2 | -8 || -13 ||| -17}

The mast of {-2 | -8} - t and -13 + t intersect at t = 4. That means that this game is ambiguous between sente and gote, but its mast value is still -13, which is the same as if it were sente. The game when we add the next value is, OC, sente.

Edited for clarity and correctness. (I missed the ambiguity. }

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Last edited by Bill Spight on Wed Oct 14, 2020 2:36 pm, edited 3 times in total.
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 Post subject: Re: Thermography #123 Posted: Wed Oct 14, 2020 12:36 pm
 Lives with ko

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It seems to me that we have a here a common understanding haven't we?
At least we have now on the table three methods that can be used to find the thermograph of a corridor and every one can have her preference.
You know my preference Bill, what is yours? BTW I suspect you could have two different preferences; one as thermography theorician and the other as go player?

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 Post subject: Re: Thermography #124 Posted: Wed Oct 14, 2020 12:54 pm
 Honinbo

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Gérard TAILLE wrote:
It seems to me that we have a here a common understanding haven't we?
At least we have now on the table three methods that can be used to find the thermograph of a corridor and every one can have her preference.
You know my preference Bill, what is yours? BTW I suspect you could have two different preferences; one as thermography theorician and the other as go player?

Well, both at the table and as an analyst, I usually guess whether a play is sente or not and try to disprove that. At the table I am generally satisfied with approximations. After all, thermography only provides heuristics. With this position at the table I would probably stop after getting the same estimate twice.

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At some point, doesn't thinking have to go on?

My two main guides in life:
My mother and my wife.

Everything with love. Stay safe.

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 Post subject: Re: Thermography #125 Posted: Wed Oct 14, 2020 1:49 pm
 Honinbo

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Using your sequence, let's make some approximations to the temperature.

6 + 4 + 5 + 6 + 2

6: max temp = 6, min = 6/2 = 3, Estimate = 4½, max error = 1½

6 + 4: max temp = 3 + 4/2 = 5, min temp = 3 + 4/4 = 4, Estimate = 4½, max error = ½ (Maybe good enough at the table. )

6 + 4 + 5: max temp = min (5, 4 + 5/4) = 5, min temp = 4⅝. Estimate = 413/16, max error = 3/16 (Very likely good enought at the table.)

6 + 4 + 5 + 6: max temp = min(5, 4⅝ + 6/8) = 5, min temp = 4⅝ + 6/16 = 5, Estimate = 5, max error = 0

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At some point, doesn't thinking have to go on?

My two main guides in life:
My mother and my wife.

Everything with love. Stay safe.

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 Post subject: Re: Thermography #126 Posted: Wed Oct 14, 2020 2:43 pm
 Lives with ko

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Bill Spight wrote:
Using your sequence, let's make some approximations to the temperature.

6 + 4 + 5 + 6 + 2

6: max temp = 6, min = 6/2 = 3, Estimate = 4½, max error = 1½

6 + 4: max temp = 3 + 4/2 = 5, min temp = 3 + 4/4 = 4, Estimate = 4½, max error = ½ (Maybe good enough at the table. )

6 + 4 + 5: max temp = min (5, 4 + 5/4) = 5, min temp = 4⅝. Estimate = 413/16, max error = 3/16 (Very likely good enought at the table.)

6 + 4 + 5 + 6: max temp = min(5, 4⅝ + 6/8) = 5, min temp = 4⅝ + 6/16 = 5, Estimate = 5, max error = 0

You have a perfect understanding of my approach Bill.
I like very much the quite efficient convergence towards the correct value with an error decreasing rapidly.

In addition taking for example the second step
6 + 4: max temp = 3 + 4/2 = 5, min temp = 3 + 4/4 = 4
in a real game, after having identifying 6 + 4, and without identifying the following 5 + 6 figures, you may see clearly that the corridor continues being quite large. In that case, with max temp = 5 and min temp = 4, your experience will tell you to take obviously max temp as a better approximation !
Yes Bill it is really a good method for a real go player and I would be not surprised to learn pro used it, without knowing the thermography background for the justification. Any information on pro estimation of a corridor?

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 Post subject: Re: Thermography #127 Posted: Wed Oct 14, 2020 2:54 pm
 Honinbo

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Gérard TAILLE wrote:
Yes Bill it is really a good method for a real go player and I would be not surprised to learn pro used it, without knowing the thermography background for the justification. Any information on pro estimation of a corridor?

AFAIK, pros have not written on any corridors besides the typical linear closed corridors that appear in textbooks. Since the Japanese edition of Mathematical Go was published in 1994, I expect that at least some pros use the techniques there. However, before publication, 9 dans flunked some of the corridor problems in the book, and I rather expect that some 9 dans today would flunk similar problems.

_________________
At some point, doesn't thinking have to go on?

My two main guides in life:
My mother and my wife.

Everything with love. Stay safe.

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 Post subject: Re: Thermography #128 Posted: Thu Oct 15, 2020 12:09 am
 Honinbo

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Maybe I spoke too soon. O Meien, in his book, Yose: Zettai Keisan (Yose: Absolute Calculation), 2004, has some short corridors.

`[go]\$\$Bc Corridors\$\$ ---------------------------------------\$\$ | X O O . O X O . O . O . O O . O O O X |\$\$ | . O X X O X X X X X O X X X X X X X X |\$\$ | X X X . O . . . . . O . . . . . X . . |\$\$ | . . . , . . . . . , . . . . . X O O X |\$\$ | . . . . . . . . . . . . . . . X X X O |\$\$ | . . . . . . . . . . . . . . . . . X O |\$\$ | . . . . . . . . . . . . . . . . . X . |\$\$ | . . . . . . . . . . . . . . . . O O O |\$\$ | . . . . . . . . . . . . . . . . . . . |\$\$ | . . . , . . . . . , . . . . . , . . . |[/go]`

All stones connected to the center are immortal.

_________________
At some point, doesn't thinking have to go on?

My two main guides in life:
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Everything with love. Stay safe.

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 Post subject: Re: Thermography #129 Posted: Thu Oct 15, 2020 4:00 am
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A special case of corridor has to be analysed in a different way : it is the common problem of answering a double sente move with another double sente move.

Let's suppose white plays a common "double sente" move which threatens to begin entering a corridor 6 + 6 + 5 + 7 and now suppose black answers with another "double sente" move which threatens another corridor 8 + 5 + 8.
Because we are talking about "double sente" move I assume the temperature of the environment is lower than 5.
What will now white play? Entering her corridor or blocking the opponent one? It seems (?) that the decision will be different if temperature is above or under t=3. I suspect a lot of mistakes can be made by real go players when facing such common situations.

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 Post subject: Re: Thermography #130 Posted: Thu Oct 15, 2020 6:52 am
 Honinbo

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Gérard TAILLE wrote:
A special case of corridor has to be analysed in a different way : it is the common problem of answering a double sente move with another double sente move.

Let's suppose white plays a common "double sente" move which threatens to begin entering a corridor 6 + 6 + 5 + 7 and now suppose black answers with another "double sente" move which threatens another corridor 8 + 5 + 8.
Because we are talking about "double sente" move I assume the temperature of the environment is lower than 5.
What will now white play? Entering her corridor or blocking the opponent one? It seems (?) that the decision will be different if temperature is above or under t=3. I suspect a lot of mistakes can be made by real go players when facing such common situations.

We have a game, {24||||18|||12||7|0} + {0|-8||-13|||-21}, is that right? The question is, which is better for White, to move to {18|||12||7|0} + {0|-8||-13|||-21} or to {3||||-3|||-9||-14|-21}. If we played the difference game, I suspect that we would find that they are incomparable. I.e.,
{18|||12||7|0} + {0|-8||-13|||-21} <> {3||||-3|||-9||-14|-21}
Since you are asking the question.

What about the thermograph of the game? Let's start by raising the ambient temperature to 3½. Now we no longer see {7|0}, but only its count, 3½. That yields

{24|||18||12|3½} + {0|-8||-13|||-21}

Now let's raise the temperature to 4. We can no longer see {0|-8}, but only its count, -4. That yields

{24|||18||12|3½} + {-4|-13||-21}

Now let's raise the temperature to 4¼. We can no longer see {12|3½}, but only its count, 7¾. That yields

{24||18|7¾} + {-4|-13||-21}

Now let's raise the temperature to 4½. We can no longer see {-4|-13}, but only its count, -8½. That yields

{24||18|7¾} + {-8½|-21}

Now let's raise the temperature to 5⅛. We can no longer see {18|7¾}, but only its count, 12⅞. That yields

{24|12⅞} + {-8½|-21}

Now let's raise the temperature to 5 9/16. That yields

18 7/16 + {-8½|-21} = {9 15/16|-2 9/16}

Now let's raise the temperature to 6¼. That yields

3 11/16

Which is the count, and the right wall of the thermograph at that temperature. The question, I take it, is to find the minimax value of play in an ideal environment at each temperature. The reduces to finding the right wall of the thermograph.

BTW, having two such hot plays remaining on the board at an ambient temperature of 3 is not at all common.

At t = 6¼ it is 3 11/16, OC.

At t = 5 9/16 it is -2 9/16 + 5 9/16 = 3.
Note that Black gets the last play. We could also find this value by subtracting 11/16 from 3 11/16.

At t = 5⅛ it is -21 + 24 = 3.
That's no surprise, since the right wall is vertical between t = t = 5⅛ and t = 5 9/16.

At t = 4½ White closes off the corridor and so does Black, for the same value of 3.
If White enters the corridor, then so does Black, for a value of -8½ + 7¾ + 4½ = 3¾, which is plainly worse.

At t = 4¼ the value is still 3.
If White enters the corridor the result will be 7¾ - 4 = 3¾.

At t = 4 the value is still 3.
If White enters the corridor the result will be 3½ - 4 + 4 = 3½.

At t = 3½ the value is still 3.
If White enters the corridor the result will be 3½ + 0 = 3½.

At t = 3 the value is still 3.
If White enters the corridor the result will be 0 + 0 + 3 = 3.

If t < 3 the value will be t. White will enter the corridor.

In an actual game, when the temperature is below 3½ or so, White will explore the possibility of getting the last play before playing in the environment.

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 Post subject: Re: Thermography #131 Posted: Thu Oct 15, 2020 8:17 am
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Looking at our previous discussion I had no idea on the way you will answer: taking the corridors from the end (pure analyst approach) or trying to take the corridor by the beginning (go player approach ?).

I fully understand your quite precise analyst approach. Let's now try to take the corridors by the beginning.
the white corridor is 6 + 6 + 5 + 7
the black corridor is 8 + 5 + 8
Because I assume the temperature of the environment lower than 5, then you can see that each player can always block the opponent corrodor in sente because the opponent should of course block immediatetly the other corridor.
Having this is mind the problem is far simplier: we imagine each player playing in their corridor and we look the opportunity for one player to block in sente the two corridors and take the environment.
Remember my only question is whether or not white has to play her first move in her corridor or for blocking black ones.

Let's proceed:
At the beginning, it is white to play and white have to choose between taking the environment (I mean blocking first the two corridors) or playing in her corridor.
1) Let'suppose white plays in her corridor => local score -6 (for black point of view)
2) if black blocks the corridor it is a success for white because black loses 6 points (the local score) while the temperature is lower (we assumed t < 5) => no choice in the context of the goal (I mean finding the best first white move) : black plays in her corridor => the local score becomes +2 (-6 and +8)
3) Because the score for black is >0 white has no choice : if the first white move in the corridor is correct then, at this stage, white must continue in her corridor for a new local score -4 (-6 -6 and +8)
4) We reach an interesting point : with a local score of -4 we see that black can choose to block the two corridors and black will gain something if the temperature of the environment is greater than 4 => first result : it t > 4 then white must choose, at her very first move to block the two corridors. Let's continue assuming t < 4. In that case black should continue her corridor for a local score of +1 (-6 -6 and +8 +5)
5) Here again, like at satge 3) above, because the score for black is >0 white has no choice => white plays in the corridor for a local score -4 (-6 -6 -5 and +8 +5)
6) The temperature of the environment being t<4 black continue in her corridor for a local score +4 (-6 -6 -5 and +8 +5 +8)
7) Here again, like at stage 3) or 5) above, because the score for black is >0 white has no choice => white plays in the corridor for a local score -3 (-6 -6 -5 -7 and +8 +5 +8). Like in point 4) above we see that all this sequence can be good for white only if t <= 3

That concludes the analysis white must block the two corridors if t > 3 and white must play in her corridor if t < 3.

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 Post subject: Re: Thermography #132 Posted: Thu Oct 15, 2020 9:34 am
 Honinbo

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Gérard TAILLE wrote:
Looking at our previous discussion I had no idea on the way you will answer: taking the corridors from the end (pure analyst approach) or trying to take the corridor by the beginning (go player approach ?).

I fully understand your quite precise analyst approach. Let's now try to take the corridors by the beginning.
the white corridor is 6 + 6 + 5 + 7
the black corridor is 8 + 5 + 8
Because I assume the temperature of the environment lower than 5, then you can see that each player can always block the opponent corrodor in sente because the opponent should of course block immediatetly the other corridor.
Having this is mind the problem is far simplier: we imagine each player playing in their corridor and we look the opportunity for one player to block in sente the two corridors and take the environment.
Remember my only question is whether or not white has to play her first move in her corridor or for blocking black ones.

The thermograph of a sum of games (positions) has not been featured here, so I took the task of at least finding the right wall of the thermograph. Maybe later I will do the left wall.

In a real game White can presumably tell that all of the gains in each corridor are at least 3½. It is also plain that if each player plays to the end of each corridor the right wall will be t at temperature t. It is also plain that if White blocks one corridor below temperature 5 (taking a quick approximation) Black will block the other one and the right wall will be at most 3 points for Black. Putting these two facts together suggests that at or below temperature 3 White should play the corridors to the end. Either player might be able to do better during the play in the corridors at a higher temperature, which would invalidate that hypothesis, so White checks that possibility.

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 Post subject: Re: Thermography #133 Posted: Thu Oct 15, 2020 12:50 pm
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Bill Spight wrote:
The thermograph of a sum of games (positions) has not been featured here, so I took the task of at least finding the right wall of the thermograph. Maybe later I will do the left wall.

In a real game White can presumably tell that all of the gains in each corridor are at least 3½. It is also plain that if each player plays to the end of each corridor the right wall will be t at temperature t. It is also plain that if White blocks one corridor below temperature 5 (taking a quick approximation) Black will block the other one and the right wall will be at most 3 points for Black. Putting these two facts together suggests that at or below temperature 3 White should play the corridors to the end. Either player might be able to do better during the play in the corridors at a higher temperature, which would invalidate that hypothesis, so White checks that possibility.

Basically I see we are now often in line concerning the understanding of the various available methods. OC, we may have different plilosophical point of view on these various methods but at least no misunderstanding. Because that was not the case at the beginning of our discussions I am quite happy because it sounds like I made some progress! Thank you Bill.

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 Post subject: Re: Thermography #134 Posted: Fri Oct 16, 2020 3:43 am
 Honinbo

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I wrote:

Bill Spight wrote:
We have a game, {24||||18|||12||7|0} + {0|-8||-13|||-21}, . . .

What about the thermograph of the game? Let's start by raising the ambient temperature to 3½. Now we no longer see {7|0}, but only its count, 3½. That yields

{24|||18||12|3½} + {0|-8||-13|||-21}

Now let's raise the temperature to 4. We can no longer see {0|-8}, but only its count, -4. That yields

{24|||18||12|3½} + {-4|-13||-21}

Now let's raise the temperature to 4¼. We can no longer see {12|3½}, but only its count, 7¾. That yields

{24||18|7¾} + {-4|-13||-21}

Now let's raise the temperature to 4½. We can no longer see {-4|-13}, but only its count, -8½. That yields

{24||18|7¾} + {-8½|-21}

Now let's raise the temperature to 5⅛. We can no longer see {18|7¾}, but only its count, 12⅞. That yields

{24|12⅞} + {-8½|-21}

Now let's raise the temperature to 5 9/16. That yields

18 7/16 + {-8½|-21} = {9 15/16|-2 9/16}

Now let's raise the temperature to 6¼. That yields

3 11/16

Which is the count, and the right wall of the thermograph at that temperature. The question, I take it, is to find the minimax value of play in an ideal environment at each temperature. . . . {I find the right wall of the thermograph, which indicates the minimax result of White playing first at each temperature.}

At t = 6¼ it is 3 11/16, OC.

At t = 5 9/16 it is -2 9/16 + 5 9/16 = 3.
Note that Black gets the last play. We could also find this value by subtracting 11/16 from 3 11/16.

At t = 5⅛ it is -21 + 24 = 3.
That's no surprise, since the right wall is vertical between t = t = 5⅛ and t = 5 9/16.

At t = 4½ White closes off the corridor and so does Black, for the same value of 3.
If White enters the corridor, then so does Black, for a value of -8½ + 7¾ + 4½ = 3¾, which is plainly worse.

At t = 4¼ the value is still 3.
If White enters the corridor the result will be 7¾ - 4 = 3¾.

At t = 4 the value is still 3.
If White enters the corridor the result will be 3½ - 4 + 4 = 3½.

At t = 3½ the value is still 3.
If White enters the corridor the result will be 3½ + 0 = 3½.

At t = 3 the value is still 3.
If White enters the corridor the result will be 0 + 0 + 3 = 3.

If t < 3 the value will be t. White will enter the corridor.

Let me now find the left wall of the thermograph, using previous calculations.

At t = 6¼ it is 3 11/16, OC.

At t = 5 9/16 it is 3 11/16 + 11/16 = 4⅜.

At t = 5⅛ it is 12⅞ - 8½ = 4⅜, no surprise.
Note that between t = 5 9/16 and t = 5⅛ this combination is double sente, since both walls of the thermograph are vertical.

At t = 4½ it is 18 - 8½ - 4½ = 5.
Black enters one corridor and then answers when White enters the other. Then White gains 4½ points by playing in the environment.

At t = 4¼ it is 18 - 13 = 5.

At t = 4 it is still 5.
If Black continues in the corridor instead, the result is 12 - 4 - 4 = 4, which is worse.

At t = 3½ it is still 5.
If Black continues to the end of the corridor the result is 0 + 3½ = 3½, which is even worse.

Below t < 3½ Black can answer White's first entry into that corridor and guarantee 5 points, or play to the end of the corridor she enters and reply to White's last play in the other corridor for a value of 7 - t. Below t = 2 that will be a good strategy.

We have found another double sente range of temperature, between t = 3 and t = 4½, where the White wall is worth 3 and the Left wall is worth 5. These double sente ranges are apparent in the thermograph.

Attachment:

dbl sente TG.png [ 4.14 KiB | Viewed 357 times ]

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 Post subject: Re: Thermography #135 Posted: Sat Oct 17, 2020 1:54 pm
 Lives with ko

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Concerning thermography how is handled yose ko?

`[go]\$\$B\$\$ -----------------\$\$ | . X X O . O . |\$\$ | O . X X O O . |\$\$ | X X X O O O O |\$\$ | O O O X X X X |\$\$ | . . . . . . . |\$\$ | . . . . . . . |\$\$ | . . . . . . . |\$\$ -----------------[/go]`

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 Post subject: Re: Thermography #136 Posted: Sat Oct 17, 2020 5:24 pm
 Honinbo

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Gérard TAILLE wrote:
Concerning thermography how is handled yose ko?

`[go]\$\$B\$\$ -----------------\$\$ | . X X O . O . |\$\$ | O . X X O O . |\$\$ | X X X O O O O |\$\$ | O O O X X X X |\$\$ | . . . . . . . |\$\$ | . . . . . . . |\$\$ | . . . . . . . |\$\$ -----------------[/go]`

You have to specify the ko threat situation. The first person who came up with a comprehensive theory of approach kos was Professor Berlekamp. It is in Games of No Chance, (Cambridge University Press, 1996). He came up with the idea of the komaster, who could win kos, but once she took a ko, had to keep going. The idea of komaster is abstract, and may not necessarily occur on the go board; but it sets what are normally practical limits on the values of complex kos.

Your example is not the simplest, so let's simplify it.

`[go]\$\$B Approach ko\$\$ ----------------------- \$\$ | X X X O . O . O X . . \$\$ | O . X X O O O O X . .\$\$ | X X X O O O . X X . .\$\$ | O O O X X X X X X . .\$\$ | . O . O X . X . X . .\$\$ | O O O O X X X X . . .\$\$ | . . . . . . . . . . .\$\$ | . . . . . . . . . . .[/go]`

White, OC, can capture the Black stones for a local score of -18. Black to play can take the ko and then fill a dame to make a direct ko, which White takes first. If Black wins the direct ko she gets a local score of +23.

If White is komaster there is not much to the play. Eventually Black will fill the dame and White will win the ko. The value of the approach ko is simply -18.

If Black is komaster, however, either White to play can win the ko, or Black to play can take the ko, fill the dame, and win the ko in one more net move. The difference between winning and losing the ko is 4 moves; so the average gain per move is 10¼ points, and the territorial value of the corner is -7¾.

That is quite a striking difference in both evaluation of territory and the size of play, and there is quite a bit to approach kos. But those are the basics of the komaster theory.

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 Post subject: Re: Thermography #137 Posted: Sun Oct 18, 2020 3:08 am
 Lives with ko

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Bill Spight wrote:
Gérard TAILLE wrote:
Concerning thermography how is handled yose ko?

`[go]\$\$B\$\$ -----------------\$\$ | . X X O . O . |\$\$ | O . X X O O . |\$\$ | X X X O O O O |\$\$ | O O O X X X X |\$\$ | . . . . . . . |\$\$ | . . . . . . . |\$\$ | . . . . . . . |\$\$ -----------------[/go]`

You have to specify the ko threat situation. The first person who came up with a comprehensive theory of approach kos was Professor Berlekamp. It is in Games of No Chance, (Cambridge University Press, 1996). He came up with the idea of the komaster, who could win kos, but once she took a ko, had to keep going. The idea of komaster is abstract, and may not necessarily occur on the go board; but it sets what are normally practical limits on the values of complex kos.

Your example is not the simplest, so let's simplify it.

`[go]\$\$B Approach ko\$\$ ----------------------- \$\$ | X X X O . O . O X . . \$\$ | O . X X O O O O X . .\$\$ | X X X O O O . X X . .\$\$ | O O O X X X X X X . .\$\$ | . O . O X . X . X . .\$\$ | O O O O X X X X . . .\$\$ | . . . . . . . . . . .\$\$ | . . . . . . . . . . .[/go]`

White, OC, can capture the Black stones for a local score of -18. Black to play can take the ko and then fill a dame to make a direct ko, which White takes first. If Black wins the direct ko she gets a local score of +23.

If White is komaster there is not much to the play. Eventually Black will fill the dame and White will win the ko. The value of the approach ko is simply -18.

If Black is komaster, however, either White to play can win the ko, or Black to play can take the ko, fill the dame, and win the ko in one more net move. The difference between winning and losing the ko is 4 moves; so the average gain per move is 10¼ points, and the territorial value of the corner is -7¾.

That is quite a striking difference in both evaluation of territory and the size of play, and there is quite a bit to approach kos. But those are the basics of the komaster theory.

Oops you changed my question Bill.

`[go]\$\$B\$\$ -----------------\$\$ | . . . . . . O |\$\$ | X X . . . . O |\$\$ | . X O O O O O |\$\$ | . X X X O . . |\$\$ | . . . X O O O |\$\$ | . . . X X X X |\$\$ | . . . . . . . |\$\$ -----------------[/go]`

When we analysed this position here above we encountered kos and we managed to take them into account in our simple non-ko ideal environment. Of course we can change the assumption on the environment and imagine ko threats or ko master configuration or whatever but my point was only to understand how taking into account a local yose ko, keeping a simple and non-ko environment.

BTW the position you proposed is in my mind completly different because, unlike mine, black to play cannot win the ko locally, I mean without the help of an external ko threat. In that sense my position seems in fact easier : comparing to a simple ko, in my position you have only to take into account that white may play in the environment one more move.
In another sense the position is OC more difficult because there are more moves in the sequence but I didn't find simplier position.
In any case assume, like our previous examples with simple kos, that we are in a non-ko environment.

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 Post subject: Re: Thermography #138 Posted: Sun Oct 18, 2020 11:02 am
 Honinbo

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Gérard TAILLE wrote:
Bill Spight wrote:
Gérard TAILLE wrote:
Concerning thermography how is handled yose ko?

`[go]\$\$B\$\$ -----------------\$\$ | . X X O . O . |\$\$ | O . X X O O . |\$\$ | X X X O O O O |\$\$ | O O O X X X X |\$\$ | . . . . . . . |\$\$ | . . . . . . . |\$\$ | . . . . . . . |\$\$ -----------------[/go]`

You have to specify the ko threat situation. The first person who came up with a comprehensive theory of approach kos was Professor Berlekamp. It is in Games of No Chance, (Cambridge University Press, 1996). He came up with the idea of the komaster, who could win kos, but once she took a ko, had to keep going. The idea of komaster is abstract, and may not necessarily occur on the go board; but it sets what are normally practical limits on the values of complex kos.

Your example is not the simplest, so let's simplify it.

Oops you changed my question Bill.

I took your question as general, not specific. My French is not good, but in French would we say. "çette yose ko", i.e., "this yose ko"?

Now, as I said, we have to specify the ko threat situation. Berlekamp's komaster idea, which does so in the abstract, gets thermographic ko theory off the ground. In the 1980s I already had the idea of an environment, and could work out very specific ko situations, but without the komaster idea I was unable to come up with a general theory. My attempts to include yose kos and other advanced kos got bogged down in complexities. Not that the idea of komaster is necessary. We can handle anything these days. But if you want to understand the thermographic theory of kos, you need to understand komaster.

Quote:
`[go]\$\$B\$\$ -----------------\$\$ | . . . . . . O |\$\$ | X X . . . . O |\$\$ | . X O O O O O |\$\$ | . X X X O . . |\$\$ | . . . X O O O |\$\$ | . . . X X X X |\$\$ | . . . . . . . |\$\$ -----------------[/go]`

When we analysed this position here above we encountered kos and we managed to take them into account in our simple non-ko ideal environment. Of course we can change the assumption on the environment and imagine ko threats or ko master configuration or whatever but my point was only to understand how taking into account a local yose ko, keeping a simple and non-ko environment.

I understand, an even applaud, your ability to jump into the river to learn how to swim. But please understand the difficulties that gives to me. How many pages do I have to write to answer a single question to someone who knows nothing about the theory? How do I make things clear? How do I justify simplifying assumptions to someone who has not struggled with the complexities? (My impression of you is that you revel in complexity. I think that's fine, but please understand my position. ) The komaster concept is an abstraction which simplifies the analysis of complex ko situations. It is not an assumption, because it does not claim that all, or even most ko situations satisfy it. By contrast, most actual go boards provide an almost ideal environment. As for komaster, in many ko situations, nobody is komaster. In many, the player who can win a ko has extra ko threats which might be useful. In such a case, I have dubbed that player a komonster. Komaster analysis provides useful signposts to help us understand ko fights. Signposts, not roadmaps.

Quote:
BTW the position you proposed is in my mind completly different

Well, yes. That's why I changed it. S'il vous plaît. I don't think it is a good introductory position for the thermography of yose ko. The other one is. From my explanation, can you draw the two komaster thermographs for it?

Quote:
because, unlike mine, black to play cannot win the ko locally, I mean without the help of an external ko threat. In that sense my position seems in fact easier : comparing to a simple ko, in my position you have only to take into account that white may play in the environment one more move.
In another sense the position is OC more difficult because there are more moves in the sequence but I didn't find simplier position.
In any case assume, like our previous examples with simple kos, that we are in a non-ko environment.

Good. You have specified the ko threat situation.

`[go]\$\$Bc Yoseko\$\$ -----------------\$\$ | . X X O . O . |\$\$ | O . X X O O . |\$\$ | X X X O O O O |\$\$ | O O O X X X X |\$\$ | ? ? ? ? ? ? ? |\$\$ | ? ? ? ? ? ? ? |\$\$ | ? ? ? ? ? ? ? |\$\$ -----------------[/go]`

For convenience, I have grayed out the rest of the board to indicate that it is no man's land, where neither side can play. OC, for thermography we assume an ideal environment somewhere.

To review, by Japanese rules if this yose ko is left on the board at the end of play, White is dead, and Black has a territory of +23. Black does not have to capture White.

`[go]\$\$Bc Black captures\$\$ -----------------\$\$ | . X X O 1 O 3 |\$\$ | O . X X O O 5 |\$\$ | X X X O O O O |\$\$ | O O O X X X X |\$\$ | ? ? ? ? ? ? ? |\$\$ | ? ? ? ? ? ? ? |\$\$ | ? ? ? ? ? ? ? |\$\$ -----------------[/go]`

If Black had to capture White, it would take her 3 moves to do so, for a territory of only +20. It would be good for White if he could force Black to do so. (BTW, I have a personal convention. As Black = Yin, feminine, and White = Yang, masculine, I refer Black as she, White as he.) Can White do that?

`[go]\$\$Wc White plays first\$\$ -----------------\$\$ | 1 X X O 2 O . |\$\$ | O . X X O O . |\$\$ | X X X O O O O |\$\$ | O O O X X X X |\$\$ | ? ? ? ? ? ? ? |\$\$ | ? ? ? ? ? ? ? |\$\$ | ? ? ? ? ? ? ? |\$\$ -----------------[/go]`

plays atari and takes the ko. Now what? has lost nothing, as added a stone to the position. Black still has only 23 points of territory.

Or does he? Under the cockamamie Japanese '89 rules, if play ends in this position Black is dead, not White! The local score is -20 on the board, but Black has captured one stone, for a net score of -19. Does Black have to capture White before end of play? If so, Black would get only 21 points of territory.

Leaving rules questions aside, Black has an immediate pressing problem. must play elsewhere. If also plays elsewhere, since there are no ko threats, can take and win the ko. (I leave that as an exercise for the reader.) Play continues.

`[go]\$\$Wc White plays first\$\$ -----------------\$\$ | 1 X X W 2 O 4 |\$\$ | O 6 X X O O 0 |\$\$ | X X X O O O O |\$\$ | O O O X X X X |\$\$ | ? ? ? ? ? ? ? |\$\$ | ? ? ? ? ? ? ? |\$\$ | ? ? ? ? ? ? ? |\$\$ -----------------[/go]`

tenuki, takes ko, @ 1, takes ko, tenuki

When the smoke has cleared, here is what we have.

`[go]\$\$Wc \$\$ -----------------\$\$ | O X X . X . X |\$\$ | . X X X . . X |\$\$ | X X X . . . . |\$\$ | O O O X X X X |\$\$ | ? ? ? ? ? ? ? |\$\$ | ? ? ? ? ? ? ? |\$\$ | ? ? ? ? ? ? ? |\$\$ -----------------[/go]`

After an even number of plays, Black has won the ko in the corner for a net score of +21 after the captured stones are counted. White has tenukied twice, for an overall result of 21 - 2t. (Yes, in real life the temperature might drop between White plays. We can handle that. To draw the thermograph we assume it stays the same. Get over it. )

Plainly Black cannot rest on his laurels and collect 23 points at the end of play. Even if White waits to start the ko at the dame stage, where t = 0, the best Black can hope for in that case is +21. And if Black takes 3 plays to capture White, she only gets +20, at most. What should Black do?

Points to ponder.

To be continued.

_________________
At some point, doesn't thinking have to go on?

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Everything with love. Stay safe.

Last edited by Bill Spight on Wed Oct 21, 2020 7:26 am, edited 1 time in total.
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 Post subject: Re: Thermography #139 Posted: Sun Oct 18, 2020 2:09 pm
 Lives with ko

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Sorry Bill for my (often) incorrect wording.

Bill Spight wrote:
`[go]\$\$Bc Yose ko\$\$ -----------------\$\$ | . X X O . O . |\$\$ | O . X X O O . |\$\$ | X X X O O O O |\$\$ | O O O X X X X |\$\$ | ? ? ? ? ? ? ? |\$\$ | ? ? ? ? ? ? ? |\$\$ | ? ? ? ? ? ? ? |\$\$ -----------------[/go]`

`[go]\$\$Bc Black captures\$\$ -----------------\$\$ | . X X O 1 O 3 |\$\$ | O . X X O O 5 |\$\$ | X X X O O O O |\$\$ | O O O X X X X |\$\$ | ? ? ? ? ? ? ? |\$\$ | ? ? ? ? ? ? ? |\$\$ | ? ? ? ? ? ? ? |\$\$ -----------------[/go]`

If Black had to capture White, it would take her 3 moves to do so, for a territory of only +20.

`[go]\$\$Bc Black captures\$\$ -----------------\$\$ | 2 X X O 3 O 1 |\$\$ | O . X X O O 5 |\$\$ | X X X O O O O |\$\$ | O O O X X X X |\$\$ | ? ? ? ? ? ? ? |\$\$ | ? ? ? ? ? ? ? |\$\$ | ? ? ? ? ? ? ? |\$\$ -----------------[/go]`

Cannot black capture with only two moves by this sequence above to reach the score +21?

I confess I missed the rule problem you mentionned. Now it sounds clearer.

Bill Spight wrote:
`[go]\$\$Wc White plays first\$\$ -----------------\$\$ | 1 X X W 2 O 4 |\$\$ | O 6 X X O O 0 |\$\$ | X X X O O O O |\$\$ | O O O X X X X |\$\$ | ? ? ? ? ? ? ? |\$\$ | ? ? ? ? ? ? ? |\$\$ | ? ? ? ? ? ? ? |\$\$ -----------------[/go]`

tenuki, takes ko, @ 1, takes ko, tenuki

...

After an even number of plays, Black has won the ko in the corner for a net score of +21 after the captured stones are counted. White has tenukied twice, for an overall result of 21 - 2t.

Because after 10 white plays again in the environment the overall result seems 21 - 2t - t/2, no?

If it is black to play the best sequence seems: black plays in the environment followed by white beginning immediatly the sequence above allowing him to get 5t/2 from the environment.

Now you see why I am asking you for the thermograph of this position: black cannot gain something by playing first in this local area but white should play here as soon as possible to get 5t/2 from the environment. It is not clear to me how left and right walls can show such result?

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 Post subject: Re: Thermography #140 Posted: Sun Oct 18, 2020 2:48 pm
 Honinbo

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Gérard TAILLE wrote:
Sorry Bill for my (often) incorrect wording.

Bill Spight wrote:
`[go]\$\$Bc Yose ko\$\$ -----------------\$\$ | . X X O . O . |\$\$ | O . X X O O . |\$\$ | X X X O O O O |\$\$ | O O O X X X X |\$\$ | ? ? ? ? ? ? ? |\$\$ | ? ? ? ? ? ? ? |\$\$ | ? ? ? ? ? ? ? |\$\$ -----------------[/go]`

`[go]\$\$Bc Black captures\$\$ -----------------\$\$ | . X X O 1 O 3 |\$\$ | O . X X O O 5 |\$\$ | X X X O O O O |\$\$ | O O O X X X X |\$\$ | ? ? ? ? ? ? ? |\$\$ | ? ? ? ? ? ? ? |\$\$ | ? ? ? ? ? ? ? |\$\$ -----------------[/go]`

If Black had to capture White, it would take her 3 moves to do so, for a territory of only +20.

`[go]\$\$Bc Black captures\$\$ -----------------\$\$ | 2 X X O 3 O 1 |\$\$ | O . X X O O 5 |\$\$ | X X X O O O O |\$\$ | O O O X X X X |\$\$ | ? ? ? ? ? ? ? |\$\$ | ? ? ? ? ? ? ? |\$\$ | ? ? ? ? ? ? ? |\$\$ -----------------[/go]`

Cannot black capture with only two moves by this sequence above to reach the score +21?

I confess I missed the rule problem you mentionned. Now it sounds clearer.

Bill Spight wrote:
`[go]\$\$Wc White plays first\$\$ -----------------\$\$ | 1 X X W 2 O 4 |\$\$ | O 6 X X O O 0 |\$\$ | X X X O O O O |\$\$ | O O O X X X X |\$\$ | ? ? ? ? ? ? ? |\$\$ | ? ? ? ? ? ? ? |\$\$ | ? ? ? ? ? ? ? |\$\$ -----------------[/go]`

tenuki, takes ko, @ 1, takes ko, tenuki

...

After an even number of plays, Black has won the ko in the corner for a net score of +21 after the captured stones are counted. White has tenukied twice, for an overall result of 21 - 2t.

Because after 10 white plays again in the environment the overall result seems 21 - 2t - t/2, no?

Sorry for not being clear. The result I meant is the right wall of the thermograph, not the estimated final score. Elsewhere I do talk about the final score, so I should have made that clear.

The walls of the thermograph are the result of the same number of plays by each player at the given temperature. Otherwise you would subtract t/2 as you have done, but then add it later, because that subtraction gives you the expected result at the end of the game, which is temperature 0, not at the current temperature. You have to adjust for that. Requiring an even number of plays is a shortcut.

Quote:
If it is black to play the best sequence seems: black plays in the environment followed by white beginning immediatly the sequence above allowing him to get 5t/2 from the environment.

Now you see why I am asking you for the thermograph of this position: black cannot gain something by playing first in this local area but white should play here as soon as possible to get 5t/2 from the environment. It is not clear to me how left and right walls can show such result?

Now you see why I wanted to start with an easier problem.

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My two main guides in life:
My mother and my wife.

Everything with love. Stay safe.

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