Life In 19x19

Posted: **Sat Apr 29, 2023 2:43 pm**

kvasir wrote:
kvasir wrote:Is it closer to 2.5 than 3? I think since the move following after black "a" is 1 2/3 sente or 4 point gote (assuming black follows up with the sente) the value in the diagram is 2 5/6.
I guess what I meant is that it's 3 2/3

I do not understand how you can reach these 2 5/6 or 3 2/3 figures. Can you explain?

Because I agree with you that the move following after black "a" is 1 2/3 sente, I guess the problem is with white to play:

Click Here To Show Diagram Code: [go]$$W $$ | . . . . . . . . . . . . $$ | . . . . . . . . . . . . $$ | . . X . . . . . . . . . $$ | . . . . . . . . . . . . $$ | . . . X . . . . . . . . $$ | . . X . O . O O O . . . $$ | . . X . . . . . . O . . $$ | . . X X O O . . . . . . $$ | . 2 1 O 3 . . . . . . . $$ -------------------------[/go]

the above sequence

is gote for white.

After this sequence if black plays the following move then we reach the following position:

Click Here To Show Diagram Code: [go]$$B $$ | . . . . . . . . . . . . $$ | . . . . . . . . . . . . $$ | . . X . . . . . . . . . $$ | . . . . . . . . . . . . $$ | . . . X . . . . . . . . $$ | . . X . O . O O O . . . $$ | . . X . . . . . . O . . $$ | . 1 X X O O . . . . . . $$ | . X O O O . . . . . . . $$ -------------------------[/go]

Otherwise if white plays the followimg move we reach the following position:

Click Here To Show Diagram Code: [go]$$W $$ | . . . . . . . . . . . . $$ | . . . . . . . . . . . . $$ | . . X . . . . . . . . . $$ | . . . . . . . . . . . . $$ | . . . X . . . . . . . . $$ | . . X . O . O O O . . . $$ | . 2 X . . . . . . O . . $$ | . 1 X X O O . . . . . . $$ | 3 X O O O . . . . . . . $$ -------------------------[/go]

I assume it will later follow

Click Here To Show Diagram Code: [go]$$W $$ | . . . . . . . . . . . . $$ | . . . . . . . . . . . . $$ | . . X . . . . . . . . . $$ | . . . . . . . . . . . . $$ | . . . X . . . . . . . . $$ | 2 . X . O . O O O . . . $$ | 1 X X . . . . . . O . . $$ | . O X X O O . . . . . . $$ | O . O O O . . . . . . . $$ -------------------------[/go]

and I assume it will also follow the following exchange

Click Here To Show Diagram Code: [go]$$B $$ | . . . . . . . . . . . . $$ | . . . . . . . . . . . . $$ | . . X . . . . . . . . . $$ | . . . . . . . . . . . . $$ | . . . X . . . . . . . . $$ | X . X . O . O O O . . . $$ | O X X . . . . . . O . . $$ | 1 O X X O O . . . . . . $$ | O 2 O O O . . . . . . . $$ -------------------------[/go]

The resulting position is

Click Here To Show Diagram Code: [go]$$B $$ | . . . . . . . . . . . . $$ | . . . . . . . . . . . . $$ | . . X . . . . . . . . . $$ | . . . . . . . . . . . . $$ | . . . X . . . . . . . . $$ | X . X b O . O O O . . . $$ | a X X . . . . . . O . . $$ | X O X X O O . . . . . . $$ | O O O O O . . . . . . . $$ -------------------------[/go]

In this position the value of a move at "a" is not equal to 1/3 because when white win the ko white can play at b and black loses at least ont other point. For me the value of a move at "a" is equal to 1/2.

Taking all that stuff, for the initial position my calculation gives the result 3 5/24 but I am not quite sure

What I am sure is that such calculation is for me too difficult and far too boring in actual game

Posted: **Sat Apr 29, 2023 3:01 pm**

Gerard, a difficult part is verifying whether White 1 to 3 is worth playing successively.

Posted: **Sat Apr 29, 2023 3:59 pm**

Gérard TAILLE wrote:I do not understand how you can reach these 2 5/6 or 3 2/3 figures. Can you explain?

Because I agree with you that the move following after black "a" is 1 2/3 sente, I guess the problem is with white to play:

The value of the follow up after white tenuki seemed too close to the original move. I assumed it would not affect the value much if we are not playing the ko as was your assumption. Maybe I should have beem clearer, I just wrote what I thought which was "it is" not "it is an estimate". I understood you to mean something similar. If white is to tenuki then that is a specific move on the board, one that I assumed is clearly less than the local move anyway, that is we pick the local move before the tenuki move. Granted that in many positions white would actually tenuki, in that case shouldn't one try to work out the whole sequence involving play in different areas instead of this move value? I guess I relay on my (faulty) spider sense in case there are close moves that should be played first, that is why I agreed that cards with endgame values could be useful.

Posted: **Sat Apr 29, 2023 5:15 pm**

"work out the whole sequence involving play in different areas instead of this move value?"

One can do so if the ensemble of sufficiently large moves is small. Otherwise, we need the local move value to relate it to the environment and must know for how long local successive play is.

Posted: **Wed May 03, 2023 1:54 pm**

Click Here To Show Diagram Code: [go]$$ $$ | . . . . . . . . . . . . $$ | . . . . . . . . . . . . $$ | . . X . . . . . . . . . $$ | . . . . . . . . . . . . $$ | . . . X . . . . . . . . $$ | . . X . O . O O O . . . $$ | . . X . . . . . . O . . $$ | . . X X O O . . . . . . $$ | . . a O . . . . . . . . $$ -------------------------[/go]

BTW Robert, how do you calculate the miai value of such position? Is it too difficult or too time consuming?

Posted: **Wed May 03, 2023 2:18 pm**

It is time-consumimg, especially when writing. I have written hundreds accurate calculations with verifications and drafted many more but do not expect me to do everybody else's work. It takes seconds to show a difficult-to-calculate position but days to write down its accurate solution. You know where you find my explanations of how to calculate and verify accurately (ignoring infinitesimals).

Posted: **Thu May 04, 2023 5:57 am**

RobertJasiek wrote:It is time-consumimg, especially when writing. I have written hundreds accurate calculations with verifications and drafted many more but do not expect me to do everybody else's work. It takes seconds to show a difficult-to-calculate position but days to write down its accurate solution. You know where you find my explanations of how to calculate and verify accurately (ignoring infinitesimals).

Yes Robert I understand using the pure theoritical approach to calculate the miai of such position is far too difficult in practice.

Searching another approach I have a pure theoritical question:

Code: Select all

Let's take the above tree : nodes C and E are supposed to be leaf nodes. Taking leaf C as the reference let's assume the count of position C is "0" and the count of position E is "e".
Now let's suppose you do not know the subtree under node D but let's suppose you know for sure that the miai value of node D is egal to vd.
My question is the following one. Can we conclude that the miai value va of node A is :
va = min(e, e/2 + vd/2)

If not can you show a counter example?

Posted: **Thu May 04, 2023 7:11 am**

Gérard TAILLE wrote:
RobertJasiek wrote:It is time-consumimg, especially when writing. I have written hundreds accurate calculations with verifications and drafted many more but do not expect me to do everybody else's work. It takes seconds to show a difficult-to-calculate position but days to write down its accurate solution. You know where you find my explanations of how to calculate and verify accurately (ignoring infinitesimals).
Yes Robert I understand using the pure theoritical approach to calculate the miai of such position is far too difficult in practice.

Searching another approach I have a pure theoritical question:
Code: Select all
               A
              / \
             /   \
            B     C
           / \  
          /   \
         D     E
        / \
       /   \
      ?     ?
Let's take the above tree : nodes C and E are supposed to be leaf nodes. Taking leaf C as the reference let's assume the count of position C is "0" and the count of position E is "e".
Now let's suppose you do not know the subtree under node D but let's suppose you know for sure that the miai value of node D is egal to vd.
My question is the following one. Can we conclude that the miai value va of node A is :
va = min(e, e/2 + vd/2)

If not can you show a counter example?

Oops, it is not exactly the tree I had in mind. Wait a little till I correct this tree. Sorry.

Posted: **Thu May 04, 2023 7:14 am**

After correction:

Code: Select all

Let's take the above tree : nodes C and E are supposed to be leaf nodes. Taking leaf C as the reference let's assume the count of position C is "0" and the count of position E is "e".
Now let's suppose you do not know the subtree under node B but let's suppose you know for sure that the miai value of node B is egal to vb.

My question is the following one. Can we conclude that the miai value va of node A is :
va = min(e, e/2 + vb/2)

If not can you show a counter example?

Posted: **Thu May 04, 2023 7:24 am**

Gérard TAILLE wrote:the pure theoritical approach to calculate the miai of such position is far too difficult in practice.

No, this is your exaggerating misreprentation. It is often not too difficult but it quickly becomes time-consuming, and writing down a practical execution of the theory applied to a difficult-to-calculate example is much more time-consuming.

Searching another approach I have a pure theoritical question:
Code: Select all
               A
              / \
             /   \
            B     C
           / \  
          /   \
         D     E
        / \
       /   \
      ?     ?
Let's take the above tree : nodes C and E are supposed to be leaf nodes. Taking leaf C as the reference let's assume the count of position C is "0" and the count of position E is "e".
Now let's suppose you do not know the subtree under node D but let's suppose you know for sure that the miai value of node D is egal to vd.
My question is the following one. Can we conclude that the miai value va of node A is :
va = min(e, e/2 + vd/2)

You have fallen back into your habit of swapping the Black = Left convention for trees; it must be max instead of min.

I am not amused by your writing vd instead of d, unnecessarily complicating matters.

Anyway, I will await your correction.

Some things that one might have to check is tree simplication theorems / methods and whether ko might disturb the task.

If not can you show a counter example?

No time.

Posted: **Thu May 04, 2023 8:13 am**

[quote="RobertJasiek"]

You have fallen back into your habit of swapping the Black = Left convention for trees; it must be max instead of min.

I am not amused by your writing vd instead of d, unnecessarily complicating matters.[quote]

Why do you suppose I did not follow the convention Black = left?
I used "vd" to avoid ambiguity between the counts a, b, c, d .. and the miai values va, vb, vc, vd. OC I am open to any other convention.

Posted: **Thu May 04, 2023 9:16 am**

I expected different things, sorry!

Please explain what you calculate here: min(e, e/2 + vb/2)

Instead of vd, I write Md, where M stands for move value, you know:) Easier! Actually I write D with capital letter as an index, which is hard here in text discussion. Bill preferred lower cases of maths annotation. I prefer upper case as easier to read amidst prose.

Posted: **Thu May 04, 2023 9:32 am**

RobertJasiek wrote:I expected different things, sorry!

Please explain what you calculate here: min(e, e/2 + vb/2)

Instead of vd, I write Md, where M stands for move value, you know:) Easier! Actually I write D with capital letter as an index, which is hard here in text discussion. Bill preferred lower cases of maths annotation. I prefer upper case as easier to read amidst prose.

As mentionned in viewtopic.php?p=277558#p277558, in my mind, the value min(e, e/2 + vb/2) is expected to be the miai value of A position.
The value "e" correspond to a sente black move (reverse sente white move) and the value e/2 + vb/2 to a gote move (black and white)

Posted: **Thu May 04, 2023 9:56 am**

I get your notation now but have not understood why you take the min. Even when I know, I do not think that I can simply answer your question. If I suspect such a condition, I try to prove it with algebra. Maybe you need CGT simplification of the type reversion. Anyway, beware of kos due to the subtree, whose impact I cannot exclude (yet).

Posted: **Thu May 04, 2023 10:17 am**

RobertJasiek wrote:I get your notation now but have not understood why you take the min. Even when I know, I do not think that I can simply answer your question. If I suspect such a condition, I try to prove it with algebra. Maybe you need CGT simplification of the type reversion. Anyway, beware of kos due to the subtree, whose impact I cannot exclude (yet).

OK let's take two examples (the first is a gote situation, the second a a (reverse) sente situation

Code: Select all


               A
              / \
             /   \
            B     C
           / \  
          /   \
         ?     E


  
               A
              / \
             /   \
            B     0
           / \  
          /   \
         7     5

vb = 1 and
va = 3 = min(5, 5/2 + 1/2)



               A
              / \
             /   \
            B     0
           / \  
          /   \
         19     5

vb = 7 and
va = 5 = min(5, 5/2 + 7/2)

OC, in the general case I consider here the node "?" may have a large subtree but I did not find a situation where my simple calculation fails. That is the point where you can surely help.

Life In 19x19

Cards or app for miai-value based endgame practice?

Re: Cards or app for miai-value based endgame practice?

Re: Cards or app for miai-value based endgame practice?

Re: Cards or app for miai-value based endgame practice?

Re: Cards or app for miai-value based endgame practice?

Re: Cards or app for miai-value based endgame practice?

Re: Cards or app for miai-value based endgame practice?

Re: Cards or app for miai-value based endgame practice?

Re: Cards or app for miai-value based endgame practice?

Re: Cards or app for miai-value based endgame practice?

Re: Cards or app for miai-value based endgame practice?

Re: Cards or app for miai-value based endgame practice?

Re: Cards or app for miai-value based endgame practice?

Re: Cards or app for miai-value based endgame practice?

Re: Cards or app for miai-value based endgame practice?

Re: Cards or app for miai-value based endgame practice?