Author: jlt [ Fri Jul 26, 2019 11:03 pm ] Post subject: Re: Please help with this exercise III @Jika: my reasoning is very down-to-earth. I just look at the triangled area Click Here To Show Diagram Code`[go]\$\$B \$\$ | . . . . . . .\$\$ | . . O . . . .\$\$ | . . . O . . .\$\$ | O O O X X . .\$\$ | T X X . . . .\$\$ | Q Q X . X . .\$\$ | T Q X . . . .\$\$ +--------------[/go]`If Black moves first then Black captures 3 stones and gets 7 points in that area, so in that area, the score (Black's points minus White's points) is 7. Click Here To Show Diagram Code`[go]\$\$B \$\$ | . . . . . . .\$\$ | . . O . . . .\$\$ | . . . O . . .\$\$ | O O O X X . .\$\$ | X X X . . . .\$\$ | P P X . X . .\$\$ | . P X . . . .\$\$ +--------------[/go]`If White moves first then White gets 1 point, so the score (Black's points minus White's points) is -1. Click Here To Show Diagram Code`[go]\$\$B \$\$ | . . . . . . .\$\$ | . . O . . . .\$\$ | . . . O . . .\$\$ | O O O X X . .\$\$ | O X X . . . .\$\$ | O O X . X . .\$\$ | . O X . . . .\$\$ +--------------[/go]`The rest of the board doesn't change, so the difference between these two situations is 7-(-1) = 8.

 Author: lightvector [ Sat Jul 27, 2019 7:22 am ] Post subject: Re: Please help with this exercise III I sort of agree with Bill. Saying a move "gains" X points suggests a few things to me, via the normal English language meaning of the word:(#1) The difference in how much a position is "worth" before and after the move is X points. (#2) If I were to pass instead, I should get a final result X points worse on average, because obviously a pass "gains" 0 points instead of X points.It's not an absolute requirement of course, but it would still be nice to have the word "gain" mean something consistent with the above two intuitions. And in double-gote positions in real games, both of these intuitive meanings are satisfied by the half the swing value: Click Here To Show Diagram Code`[go]\$\$B \$\$ . . . . . . . . .\$\$ . . . . . . . . .\$\$ . . . . . . . . .\$\$ . O O O O O O O .\$\$ . X W X . X B X .\$\$ . X a X b X c X .\$\$ . X X X X X X X .\$\$ ---------------[/go]`In situation "a" black has 0 points, in "c" black has 1 point. In situation "b", in real game situations like this, on average either player is equally likely to get it first. So on average black has 1/2 point.If black does spend a move in situation "b", black will turn it into position "c". Black's move gains half of a point because before they had 1/2 point on average, afterward they have 1 point. The difference in how much these positions is worth is half a point. (matching intuitive meaning #1 above)If black were to pass rather than playing, on average black would do 1/2 point worse. For example, if there were an odd number of positions like this left and nothing else, black end up a full 1 point worse. But if there were an even number of them, black would not end up worse at all for passing. In a real game, it's basically random whether there will be an even or odd number, so on average, black will be 1/2 point worse off by passing. (matching intuitive meaning #2 above)Similarly, if you took random pro games with a position like "b" on the board (where neither black nor white had any liberty or eye issues, both white and black were already 100% alive), and let white get a free stone at "b" near the start of the endgame, not spending their turn, and then had both players finish the endgame normally and count, on average black would do 1/2 point worse, not 1 point worse. (another variation on intuitive meaning #2 above)Explaining this requires precision on the part of the teacher, but I think if the teacher is precise, it's not particularly hard for the beginner to understand gains rather than swing values. When I teach beginners in-person, I do actually make sure to be precise when I explain move values, and the people I've taught seem to understand pretty well.-------------------------------------------------------------------------------------------------------So back to the position at hand: Click Here To Show Diagram Code`[go]\$\$\$\$ | ? ? O ? ? ?\$\$ | ? ? O ? ? ?\$\$ | O O O , ? ? \$\$ | a X X X X ?\$\$ | O O X ? ? ?\$\$ | . O X ? ? ?\$\$ +------------[/go]`With this position, if I was going to very wordily explain it in real life to someone, I'd say something like:"If black plays first, black has 7 points in the corner. If white plays first, white has 1 point, which is the same as (-1) for black. If neither player has played here yet and is busy with fighting elsewhere on the board, we expect on average 3 points for black here since knowing nothing else, either player might get to move first. So relative to that, the value/gain/worth of a move here is 4 points. If black plays first, black will do 4 points better than that (7 points) and if white plays first, white will do 4 points better than that (-1 points). Either way, the value of a move here is 4 points."And also in practice, if I was continuing to try to explain, I'd also say something like:"Many people you talk to might call this 8 points, because they're counting the total swing between black playing first and white playing first as 8 points. Note that the 8 points is actually over two moves, yours and your opponents. For example, if it was your turn, and you passed up playing here to play somewhere else instead, and then your opponent then played here instead of you, you'd get to play somewhere else again, - you would be a total of 8 points worse here compared to playing here yourself, but you'd have gotten two moves elsewhere instead, not just one, so the per-move gain/loss is still 4.Per-move values work better once you get into more complex positions that don't get finished in one move or two moves, or you start getting into cases where moves might be sente or forcing. But lots of people will talk in terms of total swing. If you personally also find it easier to think in terms of total swings for the simplest cases like this, that's also okay, just be aware of the difference and make sure you're consistent".

 Author: Bill Spight [ Sat Jul 27, 2019 8:57 am ] Post subject: Re: Please help with this exercise III Many thanks to lightvector for taking the time and effort to explain things so well. Obviously, precision in endgame evaluation is not very important. I can easily construct a problem where a mistake of 1/64 pt. or less will lose the game, but how often will such a mistake matter in real life? Still, IMHO an amateur shodan should be able to play the small endgame almost perfectly. And endgame concepts can apply at any stage of the game. I first learned endgame evaluation from the books of Sakata and Takagawa. Takagawa did a good job of evaluating plays, but both of them taught the evaluation of positions at the same time. I still remember all those Xs in Sakata's diagrams indicating points that would become territory if one player played first but would not become territory if the other player did. From Jika's remarks I get the impression that 321go did not start with the evaluation of positions, or teach it together with the evaluation of plays. But if anything, the evaluation of positions should come first. The evaluation of positions provides the conceptual basis for understanding the evaluation of plays. That is why I posted the basic problem that I did.

 Author: Jika [ Sat Jul 27, 2019 9:47 am ] Post subject: Re: Please help with this exercise III Okay, a lot to read!First, I like Kirby's approach to explain things so simply that I might understand.I get a bit confused by the more advanced discussions, but I don't really mind being confused.I'm only worried I fail expectations and waste your time.But, as I posted earlier, if I get the impression that my stupid questions spark discussions that are interesting to you all, it's good too. I can skim the discussion and if necessary ask again.You might decide this is cluttering the beginners' section.So, either one could split such a thread, or maybe I post in a different place?Would a study journal be a better place?But please know I'm happy and grateful for all answers, whether I understand them or not (in study journal I might revisit them later; only, it must be hard to keep track of all the information one gets).

 Author: Jika [ Sat Jul 27, 2019 9:51 am ] Post subject: Re: Please help with this exercise III Bill Spight wrote:OK, Jika, let's get down to basics. How much territory does White have?Hi Bill, I would have said "2".I get Ed's answer.But I never know how many possible future moves to think ahead.In this case, there are not many possible moves, and I understand why there is miai.But in other situations I don't understand how big a territory is, probably because I don't know what will be territory in future.

 Author: Jika [ Sat Jul 27, 2019 10:15 am ] Post subject: Re: Please help with this exercise III To illustrate this Quote:...in other situations I don't understand how big a territory is, probably because I don't know what will be territory in future.(and maybe drive you all nuts) a new example from 321go:(sorry, Pio, have been typing all the time, my first uploaded diagrams were not displayed) Click Here To Show Diagram Code`[go]\$\$B \$\$ | . . . , . . . . . ,\$\$ | . . . . . . . . . .\$\$ | . O . . O . . . . .\$\$ | . . O . O . . . . .\$\$ | O O . O X X . . . .\$\$ | . O O X . . . . . .\$\$ | a O X X O . . . . ,\$\$ | O X . . X X . . . .\$\$ | X . X . . . . . . .\$\$ | . . . . . . . . . .\$\$ +--------------------[/go]`They say, the value of playing at a is 2.I would have said so intuitively, because black can capture a stone.But... then I remembered that I must keep in mind that by doing so, he prevents white from getting 1 point.So, should the answer not be 2-(-1)=3?And I have no clue how far to count (see triangled intersections), given Bill/Ed's miai above...They could be getting a point there in the future, but it is not certain, as it was in the miai Ed mentioned. Click Here To Show Diagram Code`[go]\$\$BmNaN \$\$ | . . . , . . . . . ,\$\$ | . . . . . . . . . .\$\$ | . O . . O . . . . .\$\$ | . . O . O . . . . .\$\$ | O O . O X X . . . .\$\$ | . O O X . . . . . .\$\$ | X O X X O . . . . ,\$\$ | M X T . X X . . . .\$\$ | X T X . . . . . . .\$\$ | . . . . . . . . . .\$\$ +--------------------[/go]` Click Here To Show Diagram Code`[go]\$\$BmNaN \$\$ | . . . , . . . . . ,\$\$ | . . . . . . . . . .\$\$ | . O . . O . . . . .\$\$ | . T O T O . . . . .\$\$ | O O T O X X . . . .\$\$ | M O O X . . . . . .\$\$ | O O X X O . . . . ,\$\$ | O X . . X X . . . .\$\$ | X . X . . . . . . .\$\$ | . . . . . . . . . .\$\$ +--------------------[/go]`

 Author: Jika [ Sat Jul 27, 2019 10:30 am ] Post subject: Re: Please help with this exercise III And, another 50k, why is my initial diagram a gote?(People mentioned that here all the time, that's why I'm asking)I've looked at the "who has the initiative" definition of sente and gote play, but as soon as SL go into positions, terms like reverse sente and jigo are included, and I'm lost.So, is a gote position an attack into the opponent's territory he has to react to?(May I get my own forum section, Jika's question(s) of the day?)

 Author: Tryss [ Sat Jul 27, 2019 10:38 am ] Post subject: Re: Please help with this exercise III A gote move (or sequence of moves) is a sequence where the first player will also play the last move of the sequence : he will surrender the initiative to his opponent who can now play elsewhereA sente move (or sequence of moves) is a sequence where the first player won't play the last move of the sequence : he'll keep the initiative, and will play elsewhereYour initial diagram is a gote (for both player) because when the first player play, his opponent don't have to respond locally, so he'll choose where to play next.

 Author: Pio2001 [ Sat Jul 27, 2019 12:10 pm ] Post subject: Re: Please help with this exercise III Jika wrote:They say, the value of playing at a is 2.I would have said so intuitively, because black can capture a stone.But you forgot that the eye that Black is getting is a false eye "by the second line". This intersection will eventually be filled. So the capture just gets you one point thanks to the prisoner, and no point of territory.Jika wrote:But... then I remembered that I must keep in mind that by doing so, he prevents white from getting 1 point.So, should the answer not be 2-(-1)=3?Right, except that this is now 1-(-1) = 2.Jika wrote:And I have no clue how far to count (see triangled intersections)The intersections that change something must be counted. If you don't know if the triangled intersections will be affected, then you can't count the value of the endgame yet.If the status of these intersections is unclear to you, you can try a variant of the game of go against the artificial intelligence in this page : https://www.crazy-sensei.com/location=rulesIn this variant, instead of counting empty intersection plus prisoners, you just count the number of stones on the board. As long as you can add more stones, you go on, until you can't add anymore stone without being killed.This will clearly show you why the triangled intersections are stable.

 Author: Bill Spight [ Sat Jul 27, 2019 1:02 pm ] Post subject: Re: Please help with this exercise III Jika wrote:Bill Spight wrote:OK, Jika, let's get down to basics. How much territory does White have?Hi Bill, I would have said "2".Well, that's how much secure territory that White has that cannot be taken away, even if White passes all the time. (Unless White fills his own eye, OC. ) So that's a good answer. Quote:I get Ed's answer.But I never know how many possible future moves to think ahead.In this case, there are not many possible moves, and I understand why there is miai.Another, practical answer is how much territory can White defend if Black plays first? Since you get Ed's answer, you see that White can defend 3 pts. of territory. A related question is how much territory can White make, playing first, even if Black responds with best play? Since you get the miai, you see that Black can prevent White from getting more than 3 pts.OC, either player may choose to play elsewhere rather than responding locally, but White can guarantee 3 pts. of territory even if Black plays first and Black can hold White to 3 pts. of territory, even if White plays first. As a practical matter we can count White's territory as 3 pts. Quote:But in other situations I don't understand how big a territory is, probably because I don't know what will be territory in future.Join the club. ----Follow-up question:How much territory does White have, on average, at each of the 1-3 points in the top left corner?

 Author: Jika [ Sat Jul 27, 2019 10:58 pm ] Post subject: Re: Please help with this exercise III @Bill, post 53:Quote:Follow-up question:How much territory does White have, on average, at each of the 1-3 points in the top left corner? Click Here To Show Diagram Code`[go]\$\$B \$\$ +------------------\$\$ | a O b O . X . . .\$\$ | O O O C X . X . .\$\$ | c O . O X . . . .\$\$ | T O O O X . . . .\$\$ | X X X X X . . . .\$\$ | . . . . . . . . .\$\$ | . . . . . . . . .[/go]`Do you mean those?a: 1b: 1/2c: 1/2Correct??After playing at either Triangle or Circle, she would have 1+1+0=2 (I'm not counting the other eye, because you said "upper left" (then, OC, it would be 3, as seen earlier).(PS Sorry that I'm using he and she opposite to you - I'm reading "How to play Go", and they call white "she"; it would be confusing to use the opposite of what I'm reading.)
 Author: Bill Spight [ Sun Jul 28, 2019 2:35 am ] Post subject: Re: Please help with this exercise III Jika wrote:@Bill, post 53:Quote:Follow-up question:How much territory does White have, on average, at each of the 1-3 points in the top left corner? Click Here To Show Diagram Code`[go]\$\$B \$\$ +------------------\$\$ | a O b O . X . . .\$\$ | O O O C X . X . .\$\$ | c O . O X . . . .\$\$ | T O O O X . . . .\$\$ | X X X X X . . . .\$\$ | . . . . . . . . .\$\$ | . . . . . . . . .[/go]`Do you mean those?a: 1b: 1/2c: 1/2Correct??Very good. I meant b and c, which may be called 1-3 points or 3-1 points. a is a 1-1 point.Quote:(PS Sorry that I'm using he and she opposite to you - I'm reading "How to play Go", and they call white "she"; it would be confusing to use the opposite of what I'm reading.)That's fine. We are all female under the skin. (A little biological joke. Biologically, there is one human race, and the basic human body plan is female.)