Here is another problem that some people would find easy. It is smaller than the previous one, but trickier.
White to play and win.
Enjoy!
Feedback still appreciated.
| Life In 19x19 http://www.lifein19x19.com/ |
|
| One of my old problems http://www.lifein19x19.com/viewtopic.php?f=15&t=3124 |
Page 1 of 2 |
| Author: | Bill Spight [ Thu Feb 03, 2011 9:09 am ] |
| Post subject: | One of my old problems |
Here is another problem that some people would find easy. It is smaller than the previous one, but trickier. White to play and win. Enjoy! Feedback still appreciated.
|
|
| Author: | Magicwand [ Thu Feb 03, 2011 10:00 am ] |
| Post subject: | Re: One of my old problems |
edit: |
|
| Author: | Dusk Eagle [ Thu Feb 03, 2011 10:00 am ] |
| Post subject: | Re: One of my old problems |
| Author: | Bill Spight [ Thu Feb 03, 2011 10:17 am ] |
| Post subject: | Re: One of my old problems |
@ Magicwand and Dusk Eagle Thanks, guys! |
|
| Author: | HermanHiddema [ Thu Feb 03, 2011 10:33 am ] |
| Post subject: | Re: One of my old problems |
| Author: | Magicwand [ Thu Feb 03, 2011 10:41 am ] |
| Post subject: | Re: One of my old problems |
Bill Spight wrote: @ Magicwand and Dusk Eagle Thanks, guys! |
|
| Author: | Mnemonic [ Thu Feb 03, 2011 11:37 am ] |
| Post subject: | Re: One of my old problems |
I've looked at the problem for about 3-4 min and this is my first thought. I will look at it later some more to see if I missed something. (I felt this problem was easier than the last, but Bill said it was tricky  Solution: |
|
| Author: | jts [ Thu Feb 03, 2011 11:59 am ] |
| Post subject: | Re: One of my old problems |
Stab at a solution: My thoughts on the difficulty: |
|
| Author: | Dusk Eagle [ Thu Feb 03, 2011 2:07 pm ] |
| Post subject: | Re: One of my old problems |
| Author: | Bill Spight [ Thu Feb 03, 2011 4:08 pm ] |
| Post subject: | Re: One of my old problems |
Dusk Eagle wrote: |
|
| Author: | yoyoma [ Thu Feb 03, 2011 4:25 pm ] |
| Post subject: | Re: One of my old problems |
My thoughts are not 100% clear on this but I figured I'd write down what I have so far: Calculations of some of the miai values: |
|
| Author: | mitsun [ Thu Feb 03, 2011 7:38 pm ] |
| Post subject: | Re: One of my old problems |
I think the difficulty level of this problem depends on how much time you allow the solver. Anyone who can solve it in a minute or so is probably dan level. I guess a mid-kyu player could also solve it given considerably more time. |
|
| Author: | Bill Spight [ Thu Feb 03, 2011 8:05 pm ] |
| Post subject: | Re: One of my old problems |
mitsun wrote: I think the difficulty level of this problem depends on how much time you allow the solver. Anyone who can solve it in a minute or so is probably dan level. I guess a mid-kyu player could also solve it given considerably more time. |
|
| Author: | lightvector [ Thu Feb 03, 2011 11:23 pm ] |
| Post subject: | Re: One of my old problems |
Wow, I think I got it. I hope. Doing this problem has taught me a few things I didn't realize before. I think I understand much better how tedomari works. |
|
| Author: | Bill Spight [ Fri Feb 04, 2011 12:36 am ] |
| Post subject: | Re: One of my old problems |
lightvector wrote: Wow, I think I got it. I hope. Doing this problem has taught me a few things I didn't realize before. I think I understand much better how tedomari works. |
|
| Author: | Bill Spight [ Fri Feb 04, 2011 12:45 am ] |
| Post subject: | Re: One of my old problems |
Again, many thanks to the solvers. It has been enlightening to me to find out how people think about these problems, Also, it is gratifying that so many feel that they are learning something about getting the last play. I am going to pass that along to Berlekamp and Wolfe, the authors of Mathematcal Go, which is where I learned this stuff.
|
|
| Author: | walleye [ Fri Feb 04, 2011 12:54 am ] |
| Post subject: | Re: One of my old problems |
These deliberations are very interesting of course. But I'm wondering if this is the best way to improve one's endgame. In a game, most of the time it's not necessary to compute exact values of moves. It's usually enough to find the largest place and play there, taking sente and miai into account of course. Only relative size of various plays matters. Take a look at this elementary problem. How quickly can you decide which place is bigger, top or bottom? I don't really want to compute the size of plays there. What I want is something like an intuitive feel for the relative size of the two places. And a good way to develop this skill is to solve hundreds or even thousands of simple yose problems where there are only two or three unsettled boundaries left and you just have to pick the largest place. ひと目のヨセ (http://senseis.xmp.net/?YoseAtAGlance) by Cho Chikun attempts to do something like this, but it only has about a hundred problems. I need more. |
|
| Author: | lightvector [ Fri Feb 04, 2011 2:01 am ] |
| Post subject: | Re: One of my old problems |
walleye wrote: These deliberations are very interesting of course. But I'm wondering if this is the best way to improve one's endgame. In a game, most of the time it's not necessary to compute exact values of moves. It's usually enough to find the largest place and play there, taking sente and miai into account of course. Only relative size of various plays matters. Take a look at this elementary problem. How quickly can you decide which place is bigger, top or bottom? I don't really want to compute the size of plays there. What I want is something like an intuitive feel for the relative size of the two places. And a good way to develop this skill is to solve hundreds or even thousands of simple yose problems where there are only two or three unsettled boundaries left and you just have to pick the largest place. ひと目のヨセ (http://senseis.xmp.net/?YoseAtAGlance) by Cho Chikun attempts to do something like this, but it only has about a hundred problems. I need more. For common endgame moves, you don't need to compute. You can just know the values in advance, which isn't hard. The top move is 1 point because it's a gote hane+connect, the bottom is just shy of 1 because it's a corridor push. So black plays the top, solved on sight (there's also a tedomari issue, but...). I don't ever actually compute the value of a complicated move during a game, unless it's a big trade or something (and then only approximately). For me, having a few values gives a useful anchor. The following scale is roughly what I have off the top of my head, and is really useful for me in games. 1/3: Final endgame ko 1/2: Gote push to destroy 1 point 1/2 to 1: Push down corridor ending in dead end (closer to 1 if longer) 1: Sente push or push that is "eventually" sente (the corridor leads to a sente move at the end) Gote 1st line hane-connect Capture 1 stone and make 1 territory Destroy 2 points Capture2-recapture1 (this one's useful to know) 3: 1st line hane-connect sente for one side 2nd line hane-connect with gote followups Capturing 2nd line stone with gote followups 4-5: 1st line hane-connect that can't be directly blocked by one side Playing/blocking "typical" gote monkey jump ~4-10: Capturing 2nd line stone with varying senteness/severity of followups 2nd line hane connect with varying senteness/severity of followups 8 Playing/blocking "typical" sente monkey jump ~11-14+ Medium to large opening moves ~14 Opening move, taking empty corner ~N/2: Make a move that turns N potential points into dame ~N: Save N stones Resolve a small capturing race with N stones involved (owned by either player) Basically, I play a lot by feel too, but having this rough scale in mind makes it a lot easier to keep everything coherent, and helps compare things like capturing stones with first line and second line moves. It's nice to instantly know that your second line hane and connect is better than saving 4 stones from capture. |
|
| Author: | robinz [ Fri Feb 04, 2011 3:03 am ] |
| Post subject: | Re: One of my old problems |
I'm afraid to say that I've not really attempted most of these endgame problems that Bill (and others) has posted lately. And this despite me being about the 10k "target audience" - the first problem was just a bit too fiddly for me to solve at any speed, and didn't seem enough fun to want to spend time working it out I guess I need to learn from the experts here how to evaluate the size of these plays quickly. Right now I have to read out 3 or 4 moves, then compare the two positions, before I can say "OK, so A is a 2 point gote" (or whatever).Because walleye's problem is so small, it was easy enough for me to figure out that the top was bigger than the bottom, but only because I was able to read all the way to the end of the game in both cases, to see that starting on top led to a win by one whereas starting on the bottom was jigo. But it wasn't intuitively obvious to me what the answer would be from simply looking at the position. I'm not sure what this proves, other than that my endgame sucks (Although, at my club I quite often get to take white in high handicap games on small board against near-beginners; and against those who don't gratuitously let their groups die, most of my wins in these situations come from bossing them about in the endgame, so I guess my endgame isn't that terrible compared to my rank. I feel I'm OK on the general principle that you shouldn't just follow your opponent around, but make sente plays of your own if they threaten something bigger than your opponent's last "sente" play does. I'm just not very good at choosing the biggest move - particularly online when I'm always in byoyomi by the endgame, and 30 seconds just doesn't seem long enough for me to decide which the biggest areas are.) |
|
| Author: | Loons [ Fri Feb 04, 2011 4:40 am ] |
| Post subject: | Re: One of my old problems |
Considering I answered the last one correctly simply by my first pass being lucky, I will be interested in if and how I've made mistakes. I did intentionally take the last move (successfully, I believe) this time. Thanks for the fun, Bill. My Solution and slight variations: |
|
| Page 1 of 2 | All times are UTC - 8 hours [ DST ] |
| Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group http://www.phpbb.com/ |
|
is the biggest move. After that, I believe 
and 
are worth the same amount (1.0 points). However, before 
, which is sente for him (the followup is bigger than the move itself). The reason it is sente is because 'a' will not be worth a point if white can play on 
. With 
, white has obtained tedomari, and only miai plays remain.
is vital to get the last move. If 
and White needs to protect at 
and 
are miai.