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L & D for professionals
Posted: Thu Aug 19, 2010 4:54 am
by Magicwand
for those who want to solve professional level LD problem.
top professionals in Korea(choi chulhan, kim jisuk, and few more) could not solve this problem for 20 minute and gaveup.
but someone claimed that there is an answer to this problem.
lets see if anyone here can solve this problem.
$$Wcm1 Prisoners: W=0, B=0
Click Here To Show Diagram Code [go]$$Wcm1 Prisoners: W=0, B=0edit: i cound not solve this and i dont have answer.
i am hoping someone or i can comeup with correct answer soon.
Re: L & D for professionals
Posted: Thu Aug 19, 2010 5:41 am
by gowan
Magicwand wrote: for those who want to solve professional level LD problem.
top professionals in Korea(choi chulhan, kim jisuk, and few more) could not solve this problem for 20 minute and gaveup.
but someone claimed that there is an answer to this problem.
lets see if anyone here can solve this problem.
$$Wcm1 Prisoners: W=0, B=0
Click Here To Show Diagram Code [go]$$Wcm1 Prisoners: W=0, B=0Black to play right?
Re: L & D for professionals
Posted: Thu Aug 19, 2010 6:06 am
by kirkmc
How do you know it's even solvable? In other words, assuming it's black to play, are you sure that black can kill?
Re: L & D for professionals
Posted: Thu Aug 19, 2010 6:37 am
by Magicwand
gowan wrote: Black to play right?
yes black to play.
i saw the video and many professionals tried
as a first move..and could not solve it. it might help you solve them.
$$Bcm1 Prisoners: W=0, B=0
Click Here To Show Diagram Code [go]$$Bcm1 Prisoners: W=0, B=0
Re: L & D for professionals
Posted: Thu Aug 19, 2010 6:39 am
by Magicwand
kirkmc wrote: How do you know it's even solvable? In other words, assuming it's black to play, are you sure that black can kill?
i am pretty sure there is an answer. according to the video one website made a page dedicated to this problem. i am thinking they will not do that if it has no solution.
Re: L & D for professionals
Posted: Thu Aug 19, 2010 7:56 am
by prokofiev
A few thoughts that are perhaps obvious:
It seems that if you don't play O19, White gets an easy eye:
$$Bcm1 Prisoners: W=0, B=0
Click Here To Show Diagram Code [go]$$Bcm1 Prisoners: W=0, B=0Edit: Nevermind. I had some idea about ignoring M19, but it clearly does not work...
Re: L & D for professionals
Posted: Thu Aug 19, 2010 10:29 am
by Numsgil
Hmm, when you dig in to this problem there are some interesting half-sequences to consider. Consider the usual fundamentals for L&D: reduce eye space to a killable shape and then play the vital point.
So let's consider the hane on the right.
This sequence here is bad for white, certainly. So if black hanes here, white can't counter hane
and save the stones.
$$Bc 6 at 3
Click Here To Show Diagram Code [go]$$Bc 6 at 3
So then something like this comes to mind. White dies if he plays like this, too.
$$Bc
Click Here To Show Diagram Code [go]$$Bc
So what if white falls back?
$$Bc
Click Here To Show Diagram Code [go]$$BcNot a local capture, but we force white to try and live in the center maybe. Assuming play up to here is optimal for either side, is there a trick to contain and kill the white group from here?
$$Bc
Click Here To Show Diagram Code [go]$$BcAnyway, those are my thoughts. Maybe a stronger player can take them and run with it.
Re: L & D for professionals
Posted: Thu Aug 19, 2010 10:54 am
by prokofiev
Numsgil: In your last diagram, white can play 2 at J17 and make an eye easily.
Re: L & D for professionals
Posted: Thu Aug 19, 2010 11:09 am
by Cassandra
Numsgil wrote: Hmm, when you dig in to this problem there are some interesting half-sequences to consider. Consider the usual fundamentals for L&D: reduce eye space to a killable shape and then play the vital point.
White will not die with the sequences shown.
$$Bc
Click Here To Show Diagram Code [go]$$BcI suppose White will play
from below.
$$Bc
Click Here To Show Diagram Code [go]$$BcAnd thereafter with
what has been mentioned to be the vital point of this problem.
Black loses some tempo because he must connect at a and b. And c remains as Sente for White, too.
Re: L & D for professionals
Posted: Thu Aug 19, 2010 11:43 am
by Numsgil
@Cassandra:
Ah yes. Figured there was a good refutation since it's a hard problem and I'm not a strong L&D-er.
Still, I think that's the right track. Maybe do some other stuff first before the hane. The hane there has a
lot of aji. More than it really looks like it should (to my eyes anyway). So I think it's just a matter of figuring out when the time is right to activate it.
...
Are we absolutely sure that 'c' in your diagram is sente? Capturing two stones doesn't give white an eye, after all, since it has a defect. It's just a matter of containing white so he can't make another eye further along the edge. I'm wondering if there's a clever tesuji that would work here.
...
Are there any under the stones play that would be at all useful here?
$$Wc
Click Here To Show Diagram Code [go]$$Wc$$Bc
Click Here To Show Diagram Code [go]$$BcThe above doesn't work ('a' and 'b' are miai), but it's close (in that if black had one more move here, or a shortage of liberties to take advantage of for the throw in, it would work) and the sort of tricky stuff I'd expect from a hard problem. So maybe do some stuff first to prep for this somehow.
...
Also, what about something like this (both sides ignoring the left black stones in atari). You start a ko (I'm not sure the type name. Two step?). Obviously those black stones in atari sort of muck things up a bit. But if black wins the ko white has no eyes on the right so that's maybe something? Is there a way to then contain white to just a single eye on the left?
$$Bc
Click Here To Show Diagram Code [go]$$BcNothing quite works yet but I feel like these are some pieces of the puzzle.
@prokofiev:
Hmm, yeah, something like this doesn't work for black.
$$Bc
Click Here To Show Diagram Code [go]$$BcTrying to be tricky doesn't really help either.
$$Bc
Click Here To Show Diagram Code [go]$$Bc
Re: L & D for professionals
Posted: Thu Aug 19, 2010 10:17 pm
by ethanb
Q18 is interesting. How does white respond?
$$Bcm1 Looks dead
Click Here To Show Diagram Code [go]$$Bcm1 Looks dead$$Bcm1 Dead too
Click Here To Show Diagram Code [go]$$Bcm1 Dead too$$Bcm1 Connection back doesn't work
Click Here To Show Diagram Code [go]$$Bcm1 Connection back doesn't work$$Bcm1 Ah, tesuji?
Click Here To Show Diagram Code [go]$$Bcm1 Ah, tesuji?
Re: L & D for professionals
Posted: Thu Aug 19, 2010 11:10 pm
by unkx80
I haven't found any solution yet.
@ethanb: How do you deal with the following?
$$Bcm1 Looks dead
Click Here To Show Diagram Code [go]$$Bcm1 Looks dead
Re: L & D for professionals
Posted: Thu Aug 19, 2010 11:15 pm
by Cassandra
@Numsgil:
You have to mind the order of moves
$$Bc
Click Here To Show Diagram Code [go]$$Bc$$Wcm10
Click Here To Show Diagram Code [go]$$Wcm10Black cannot connect at a, because White c is Double-Atari then.
If Black plays c, White gets a Double-Ko at a and b.
Re: L & D for professionals
Posted: Thu Aug 19, 2010 11:54 pm
by ethanb
unkx80 wrote: I haven't found any solution yet.
@ethanb: How do you deal with the following?
$$Bcm1 Looks dead
Click Here To Show Diagram Code [go]$$Bcm1 Looks deadAt least I never claimed to not be an idiot
But I still feel good about Q18 - I'm going to study it some and see if there's a non-obvious sequence after Q17. Under the stones eye stealing or something, maybe.
Re: L & D for professionals
Posted: Fri Aug 20, 2010 2:54 am
by Cassandra
ethanb wrote: But I still feel good about Q18 - I'm going to study it some and see if there's a non-obvious sequence after Q17. Under the stones eye stealing or something, maybe.
$$Bcm1
Click Here To Show Diagram Code [go]$$Bcm1There are some problems, where
is the Tesuji.
But here Black cannot do anything on the left, so there is no Miai with the potential Ko on the right.
Preventing White's Sente on the left immediately ...
... will not work, I suppose.
$$Bcm1
Click Here To Show Diagram Code [go]$$Bcm1
as a first move..and could not solve it. it might help you solve them.
from below.
what has been mentioned to be the vital point of this problem.
is the Tesuji.