Life In 19x19 :: L19 Go Problem Championship: Round 3

1. Two eyes

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

2. Clamp

Click Here To Show Diagram Code: [go]$$Bc $$ | . . . . . . . . . $$ | . . . . . . . . . $$ | . . . X . . . . . $$ | . X X . X X . . . $$ | 5 X O O O X . . . $$ | 2 O 3 6 . X . X . $$ | 7 1 4 O . . . . . $$ | . . . . . . . . . $$ ------------------[/go]

Variation: B3 might leave to a little more complicated variations, but still kills

Click Here To Show Diagram Code: [go]$$Bc $$ | . . . . . . . . . $$ | . . . . . . . . . $$ | . . . X . . . . . $$ | . X X . X X . . . $$ | . X O O O X . . . $$ | 2 O 4 9 5 X . X . $$ | 6 1 3 O 8 c d . . $$ | a 7 b f . e . . . $$ ------------------[/go]

Variation: Ko, B fails

Click Here To Show Diagram Code: [go]$$Bc $$ | . . . . . . . . . $$ | . . . . . . . . . $$ | . . . X . . . . . $$ | . X X . X X . . . $$ | 4 X O O O X . . . $$ | 1 O 5 . . X . X . $$ | 2 3 6 O . . . . . $$ | . . . . . . . . . $$ ------------------[/go]

Variation: B fails

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

Click Here To Show Diagram Code: [go]$$Bc $$ | . . . . . . . . . $$ | X X X X . . . . . $$ | X O O 7 X X . . . $$ | O 6 3 4 O X . X . $$ | . O 2 1 5 O . . . $$ | . . . . . . . . . $$ ------------------[/go]

Variation:

Click Here To Show Diagram Code: [go]$$Bc $$ | . . . . . . . . . $$ | X X X X . . . . . $$ | X O O , X X . . . $$ | O . 2 4 O X . X . $$ | . O 3 1 5 O . . . $$ | . . . . . . . . . $$ ------------------[/go]

Variation: after 3, a and b are miai

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

Variation: B fails - order matters

Click Here To Show Diagram Code: [go]$$Bc $$ | . . . . . . . . . $$ | X X X X . . . . . $$ | X O O , X X . . . $$ | O . 1 2 O X . X . $$ | . O . 3 4 O . . . $$ | . . . . . . . . . $$ ------------------[/go]

Variation: B fails

Click Here To Show Diagram Code: [go]$$Bc $$ | . . . . . . . . . $$ | X X X X . . . . . $$ | X O O , X X . . . $$ | O . 3 2 O X . X . $$ | . O 1 4 . O . . . $$ | . . . . . . . . . $$ ------------------[/go]

Variation: B fails

Click Here To Show Diagram Code: [go]$$Bc $$ | . . . . . . . . . $$ | X X X X . . . . . $$ | X O O , X X . . . $$ | O . 2 1 O X . X . $$ | . O 4 3 . O . . . $$ | . . . . . . . . . $$ ------------------[/go]

2017 Round 3.1 (007)

tenuki, alive

Click Here To Show Diagram Code: [go]$$B tenuki, alive $$------------------ $$ | . 1 2 4 . O . . $$ | X O 3 . . O . . $$ | . X X X O O . . $$ | a O O O O . . . $$ | b . . . . . . . $$ | . . . . . . . .[/go]

Careful: Later, W has sente moves (a), (b).

2017 Round 3.2 (008)

Click Here To Show Diagram Code: [go]$$B $$ | . . . . . . . . . $$ | . . . X . . . . . $$ | . X X . X X . . . $$ | 5 X O O O X . . . $$ | 2 O 3 6 . X . X . $$ | 7 1 4 O . . . . . $$ | . . . . . . . . . $$ ------------------[/go]

(c), (d) miai: W seems dead this var

Click Here To Show Diagram Code: [go]$$Wm8 (c), (d) miai: W seems dead this var $$ | . . . . . . . . . $$ | . . . X . . . . . $$ | . X X . X X . . . $$ | X X O O O X . . . $$ | O O 1 O . X . X . $$ | X X O O 2 . . . . $$ | . c . d . . . . . $$ ------------------[/go]

2017 Round 3.3 (009) :study:

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

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

Click Here To Show Diagram Code: [go]$$B $$ | . . . . . . . . . $$ | X X X X . . . . . $$ | X O O 7 X X . . . $$ | O 6 3 4 O X . X . $$ | . O 2 1 5 O . . . $$ | . . . . . . . . . $$ ------------------[/go]

W dead

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

W dead

Click Here To Show Diagram Code: [go]$$B W dead $$ | . . . . . . . . . $$ | X X X X . . . . . $$ | X O O , X X . . . $$ | O . 5 2 O X . X . $$ | . O 4 1 3 O . . . $$ | . . . . . . . . . $$ ------------------[/go]

W dead

Click Here To Show Diagram Code: [go]$$B W dead $$ | . . . . . . . . . $$ | X X X X . . . . . $$ | X O O , X X . . . $$ | O . 2 4 O X . X . $$ | . O 3 1 5 O . . . $$ | . . . . . . . . . $$ ------------------[/go]

Author:	gamesorry [ Fri Mar 03, 2017 12:50 am ]
Post subject:	Re: L19 Go Problem Championship: Round 3
1. Two eyes Click Here To Show Diagram Code `[go]$$Bc $$ ---------------- $$ \| . 1 . . . O . . $$ \| X O . . . O . . $$ \| . X X X O . O . $$ \| . O O O O . . . $$ \| . . . . . . . .[/go]` 2. Clamp Click Here To Show Diagram Code `[go]$$Bc $$ \| . . . . . . . . . $$ \| . . . . . . . . . $$ \| . . . X . . . . . $$ \| . X X . X X . . . $$ \| 5 X O O O X . . . $$ \| 2 O 3 6 . X . X . $$ \| 7 1 4 O . . . . . $$ \| . . . . . . . . . $$ ------------------[/go]` Variation: B3 might leave to a little more complicated variations, but still kills Click Here To Show Diagram Code `[go]$$Bc $$ \| . . . . . . . . . $$ \| . . . . . . . . . $$ \| . . . X . . . . . $$ \| . X X . X X . . . $$ \| . X O O O X . . . $$ \| 2 O 4 9 5 X . X . $$ \| 6 1 3 O 8 c d . . $$ \| a 7 b f . e . . . $$ ------------------[/go]` Variation: Ko, B fails Click Here To Show Diagram Code `[go]$$Bc $$ \| . . . . . . . . . $$ \| . . . . . . . . . $$ \| . . . X . . . . . $$ \| . X X . X X . . . $$ \| 4 X O O O X . . . $$ \| 1 O 5 . . X . X . $$ \| 2 3 6 O . . . . . $$ \| . . . . . . . . . $$ ------------------[/go]` Variation: B fails Click Here To Show Diagram Code `[go]$$Bc $$ \| . . . . . . . . . $$ \| . . . . . . . . . $$ \| . . . X . . . . . $$ \| . X X . X X . . . $$ \| . X O O O X . . . $$ \| . O . . . X . X . $$ \| . . 2 O 1 . . . . $$ \| . . . . . . . . . $$ ------------------[/go]` 3. Click Here To Show Diagram Code `[go]$$Bc $$ \| . . . . . . . . . $$ \| X X X X . . . . . $$ \| X O O 7 X X . . . $$ \| O 6 3 4 O X . X . $$ \| . O 2 1 5 O . . . $$ \| . . . . . . . . . $$ ------------------[/go]` Variation: Click Here To Show Diagram Code `[go]$$Bc $$ \| . . . . . . . . . $$ \| X X X X . . . . . $$ \| X O O , X X . . . $$ \| O . 2 4 O X . X . $$ \| . O 3 1 5 O . . . $$ \| . . . . . . . . . $$ ------------------[/go]` Variation: after 3, a and b are miai Click Here To Show Diagram Code `[go]$$Bc $$ \| . . . . . . . . . $$ \| X X X X . . . . . $$ \| X O O , X X . . . $$ \| O . b 2 O X . X . $$ \| . O a 1 3 O . . . $$ \| . . . . . . . . . $$ ------------------[/go]` Variation: B fails - order matters Click Here To Show Diagram Code `[go]$$Bc $$ \| . . . . . . . . . $$ \| X X X X . . . . . $$ \| X O O , X X . . . $$ \| O . 1 2 O X . X . $$ \| . O . 3 4 O . . . $$ \| . . . . . . . . . $$ ------------------[/go]` Variation: B fails Click Here To Show Diagram Code `[go]$$Bc $$ \| . . . . . . . . . $$ \| X X X X . . . . . $$ \| X O O , X X . . . $$ \| O . 3 2 O X . X . $$ \| . O 1 4 . O . . . $$ \| . . . . . . . . . $$ ------------------[/go]` Variation: B fails Click Here To Show Diagram Code `[go]$$Bc $$ \| . . . . . . . . . $$ \| X X X X . . . . . $$ \| X O O , X X . . . $$ \| O . 2 1 O X . X . $$ \| . O 4 3 . O . . . $$ \| . . . . . . . . . $$ ------------------[/go]`

Author:	Kirby [ Fri Mar 03, 2017 12:52 am ]
Post subject:	Re: L19 Go Problem Championship: Round 3
@gamesorry: Perfect. A little easy this week, I guess

Author:	gamesorry [ Fri Mar 03, 2017 1:00 am ]
Post subject:	Re: L19 Go Problem Championship: Round 3
@Kirby Kirby wrote: @gamesorry: Perfect. A little easy this week, I guess Thanks I think problem 3 is easier than before because the best result is not a ko. But still, good problems!

Author:	Kirby [ Fri Mar 03, 2017 1:04 am ]
Post subject:	Re: L19 Go Problem Championship: Round 3
gamesorry wrote: @Kirby Kirby wrote: @gamesorry: Perfect. A little easy this week, I guess Thanks I think problem 3 is easier than before because the best result is not a ko. But still, good problems! @gamesorry: The competition at my work is two weeks ahead, and I think the next round might be a bit trickier, based on responses I got from participants there. I guess we'll see next week.

Author:	EdLee [ Fri Mar 03, 2017 3:42 am ]
Post subject:
2017 Round 3.1 (007) tenuki, alive Click Here To Show Diagram Code `[go]$$B tenuki, alive $$------------------ $$ \| . 1 2 4 . O . . $$ \| X O 3 . . O . . $$ \| . X X X O O . . $$ \| a O O O O . . . $$ \| b . . . . . . . $$ \| . . . . . . . .[/go]` Careful: Later, W has sente moves (a), (b). 2017 Round 3.2 (008) Click Here To Show Diagram Code `[go]$$B $$ \| . . . . . . . . . $$ \| . . . X . . . . . $$ \| . X X . X X . . . $$ \| 5 X O O O X . . . $$ \| 2 O 3 6 . X . X . $$ \| 7 1 4 O . . . . . $$ \| . . . . . . . . . $$ ------------------[/go]` (c), (d) miai: W seems dead this var Click Here To Show Diagram Code `[go]$$Wm8 (c), (d) miai: W seems dead this var $$ \| . . . . . . . . . $$ \| . . . X . . . . . $$ \| . X X . X X . . . $$ \| X X O O O X . . . $$ \| O O 1 O . X . X . $$ \| X X O O 2 . . . . $$ \| . c . d . . . . . $$ ------------------[/go]` 2017 Round 3.3 (009) Click Here To Show Diagram Code `[go]$$B $$ \| . . . . . . . . . $$ \| X X X X . . . . . $$ \| X O O , X X . . . $$ \| O . . . O X . X . $$ \| . O . 1 . O . . . $$ \| . . . . . . . . . $$ ------------------[/go]` Click Here To Show Diagram Code `[go]$$B $$ \| . . . . . . . . . $$ \| X X X X . . . . . $$ \| X O O , X X . . . $$ \| O . 3 . O X . X . $$ \| . O 2 1 . O . . . $$ \| . . . . . . . . . $$ ------------------[/go]` Click Here To Show Diagram Code `[go]$$B $$ \| . . . . . . . . . $$ \| X X X X . . . . . $$ \| X O O 7 X X . . . $$ \| O 6 3 4 O X . X . $$ \| . O 2 1 5 O . . . $$ \| . . . . . . . . . $$ ------------------[/go]` W dead Click Here To Show Diagram Code `[go]$$B W dead $$ \| . . . . . . . . . $$ \| X X X X . . . . . $$ \| X O O X X X . . . $$ \| O O . O O X . X . $$ \| . O O X X O . . . $$ \| . . . . . . . . . $$ ------------------[/go]` W dead Click Here To Show Diagram Code `[go]$$B W dead $$ \| . . . . . . . . . $$ \| X X X X . . . . . $$ \| X O O , X X . . . $$ \| O . 5 2 O X . X . $$ \| . O 4 1 3 O . . . $$ \| . . . . . . . . . $$ ------------------[/go]` W dead Click Here To Show Diagram Code `[go]$$B W dead $$ \| . . . . . . . . . $$ \| X X X X . . . . . $$ \| X O O , X X . . . $$ \| O . 2 4 O X . X . $$ \| . O 3 1 5 O . . . $$ \| . . . . . . . . . $$ ------------------[/go]`

Life In 19x19 http://www.lifein19x19.com/

L19 Go Problem Championship: Round 3 http://www.lifein19x19.com/viewtopic.php?f=15&t=14054	Page 1 of 1

Author:	Kirby [ Fri Mar 03, 2017 8:44 am ]
Post subject:	Re: L19 Go Problem Championship: Round 3
@EdLee Problem 1: Can you get better than ko? Problem 2: Looks good!

Author:	mongus [ Sat Mar 04, 2017 4:22 am ]
Post subject:	Re: L19 Go Problem Championship: Round 3
Problem 1 Click Here To Show Diagram Code `[go]$$Bc $$ ---------------- $$ \| . 1 . . . O . . $$ \| X O 2 3 . O . . $$ \| . X X X O . O . $$ \| . O O O O . . . $$ \| . . . . . . . .[/go]` or Click Here To Show Diagram Code `[go]$$Bc $$ ---------------- $$ \| . 1 . . . O . . $$ \| X O 3 2 . O . . $$ \| . X X X O . O . $$ \| . O O O O . . . $$ \| . . . . . . . .[/go]` Problem 2 Click Here To Show Diagram Code `[go]$$Bc $$ \| . . . . . . . . . $$ \| . . . . . . . . . $$ \| . . . X . . . . . $$ \| . X X . X X . . . $$ \| . X O O O X . . . $$ \| 4 O . 2 1 X . X . $$ \| . 3 5 O . . . . . $$ \| . . . . . . . . . $$ ------------------[/go]`

Author:	Shaddy [ Sat Mar 04, 2017 11:16 pm ]
Post subject:	Re: L19 Go Problem Championship: Round 3
Problem 1 (3 points) Click Here To Show Diagram Code `[go]$$Bc $$ ---------------- $$ \| . 1 . . . O . . $$ \| X O . . . O . . $$ \| . X X X O . O . $$ \| . O O O O . . . $$ \| . . . . . . . .[/go]` Problem 2 (6 points) Click Here To Show Diagram Code `[go]$$Bc $$ \| . . . . . . . . . $$ \| . . . . . . . . . $$ \| . . . X . . . . . $$ \| . X X . X X . . . $$ \| 7 X O O O X . . . $$ \| 2 O 3 6 . X . X . $$ \| 5 1 4 O 9 . . . . $$ \| . . . . . . . . . $$ ------------------[/go]` 8 @ 3 Problem 3 (9 points) Click Here To Show Diagram Code `[go]$$Bc $$ \| . . . . . . . . . $$ \| X X X X . . . . . $$ \| X O O 7 X X . . . $$ \| O 6 3 4 O X . X . $$ \| . O 2 1 5 O . . . $$ \| . . . . . . . . . $$ ------------------[/go]`

Author:	Kirby [ Sat Mar 04, 2017 11:21 pm ]
Post subject:	Re: L19 Go Problem Championship: Round 3
@mongus: Problem 1: OK! Problem 2: If white plays as below...? Click Here To Show Diagram Code `[go]$$Bc $$ \| . . . . . . . . . $$ \| . . . . . . . . . $$ \| . . . X . . . . . $$ \| . X X . X X . . . $$ \| . X O O O X . . . $$ \| . O . . 1 X . X . $$ \| . 2 . O . . . . . $$ \| . . . . . . . . . $$ ------------------[/go]`

Author:	Kirby [ Sat Mar 04, 2017 11:22 pm ]
Post subject:	Re: L19 Go Problem Championship: Round 3
@Shaddy: Looks good.

Author:	mongus [ Mon Mar 06, 2017 11:44 am ]
Post subject:	Re: L19 Go Problem Championship: Round 3
@Kirby Ah, hadn't thought about that. I think this works better. Click Here To Show Diagram Code `[go]$$Bc $$ \| . . . . . . . . . $$ \| . . . . . . . . . $$ \| . . . X . . . . . $$ \| . X X . X X . . . $$ \| . X O O O X . . . $$ \| 2 O . 4 3 X . X . $$ \| . 1 5 O 6 7 . . . $$ \| . . 9 . 8 . . . . $$ ------------------[/go]`

Author:	Kirby [ Tue Mar 07, 2017 3:08 pm ]
Post subject:	Re: L19 Go Problem Championship: Round 3
@mongus: How about if white responds with , as below? Click Here To Show Diagram Code `[go]$$Bc $$ \| . . . . . . . . . $$ \| . . . . . . . . . $$ \| . . . X . . . . . $$ \| . X X . X X . . . $$ \| . X O O O X . . . $$ \| 2 O . . 3 X . X . $$ \| . 1 4 O . . . . . $$ \| . . . . . . . . . $$ ------------------[/go]`

Author:	Kirby [ Thu Mar 09, 2017 11:52 pm ]
Post subject:	Re: L19 Go Problem Championship: Round 3
Solutions and an updated leaderboard are given below. Problem 1 (;GM[1]FF[4]CA[UTF-8]AP[WebGoBoard:0.10.8]ST[0]SZ[19]KM[0]HA[0]PB[Black]PW[White]AB[ab][bc][cc][dc]AW[bb][bd][cd][dd][ed][ec][fb][fa][gc]C[Problem 1: Black lives unconditionally.](;B[ba]C[B19, the 1-2 point, guarantees two eyes.];W[ca]C[Playing at C19 almost looks like it creates shape for a false eye, but not really.];B[cb];W[da]C[Black is alive with two eyes.])(;B[cb]C[Starting from C18 is a mistake.];W[ba]C[Black is dead, now.])) Problem 2 (;GM[1]FF[4]CA[UTF-8]AP[WebGoBoard:0.10.8]ST[0]SZ[19]KM[0]HA[0]PB[Black]PW[White]AB[bp][bo][co][dn][eo][fo][fp][fq][hq]AW[cp][dp][ep][dr][bq]C[Problem 2: Black kills.](;B[br]C[B2 is the key move to kill white.];W[aq];B[cq]C[C3 creates a shortage of liberties, which allows black to squeeze white down to one eye.];W[cr];B[ar];W[dq];B[ap];W[cq];B[er]C[White is dead.])(;B[aq]C[Starting from the outside is typically a good idea, but in this case, black fails.];W[br];B[ar];W[fr]C[White F2 creates sufficient eyespace to live.](;B[gr];W[er])(;B[eq];W[er];B[dq];W[cq];B[cs];W[hr]))) Problem 3 (;GM[1]FF[4]CA[UTF-8]AP[WebGoBoard:0.10.8]ST[0]SZ[19]KM[0]HA[0]PB[Black]PW[White]AB[ap][ao][bo][co][do][ep][fp][fq][hq]AW[fr][eq][cp][bp][aq][br]C[Problem 3: Black kills.](;B[dq]C[Splitting white apart appears to be a good idea. However, white can sacrifice some stones to live with the main group in the corner.];W[cq]C[White now has a living shape, even if E3 is captured.];B[dr];W[cr]C[White lives.])(;B[cr]C[C2 looks like a key shape move, but it fails.];W[dr]C[White D2 creates enough eyespace for white to live.];B[dq];W[cq];B[er];W[cs]C[White lives.])(;B[dr]C[Black D2 is the key move.];W[dq];B[er]C[Surprisingly, white no longer has space to live.];W[cr];B[cq]C[The throwin at C3 reduces white to one eye.];W[bq];B[dp];W[cq];B[gr]C[White is dead.])) Leaderboard gamesorry - 54 Shaddy - 36 EdLee - 28 Schachus - 23 Lanrose - 16 jeromie - 13 dfan - 12 mongus - 4 Round 4 will be released shortly!

Author:	mongus [ Fri Mar 10, 2017 2:58 am ]
Post subject:	Re: L19 Go Problem Championship: Round 3
Many thanks for doing these. Great explanation of the solutions. I have a lot of catching up to do!

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Author:	Kirby [ Fri Mar 10, 2017 7:28 am ]
Post subject:	Re: L19 Go Problem Championship: Round 3
mongus wrote: Many thanks for doing these. Great explanation of the solutions. I have a lot of catching up to do! In my experience in holding this competition at my work, persistence pays off. Even if you don't get the right solution every week, trying every time helps.