L19 Go Problem Championship: Round 1

Kirby · Post by **Kirby** » Fri Feb 03, 2017 4:12 pm

For the past couple of years, I've put forth an annual go problem competition where I work.

The premise is simple:

Every Friday, I put up three go problems. I try to choose one that's easy, moderate, and difficult for me to personally solve. Since I'm the one that selects the difficulty, sometimes the problems difficulty isn't evenly distributed according to the difficulty level I select... But it is what it is.
To attempt a problem, you email me the variations that you come up with, and I respond indicating that the solution is correct, incorrect, or in need of clarification (i.e. additional variation in case white plays a different way). I'll do so through PM, so check your PM inbox after posting the problem.
If you get a problem correct, you gain the points associated with that problem. If you get the problem incorrect, you can keep trying for the rest of the week, until I submit the solutions. If you attempted a problem, but didn't get it correct, you get partial points for participation.

Then, at the end of the year, we have a potluck-style awards ceremony where I buy prizes for the top three participants, as well as an additional prize for the person that participated the most, but wasn't in the top 3. It's usually pretty fun, so I'm starting it again this year for 2017.

Since I'm already doing this for my work, I figured I'd hold a mini-competition here, as well: I'll post the same problems, and you can participate to be the L19 Go Problem Champion for 2017.

If you want to play, just post your solution to one or more problems any week that I post them by either:

PM to my account here on L19; or
Use hide tags to post your variations under the thread in which I post the problems.

If you decide to participate, we'll go on the honor system regarding cheating. Please don't look at the hide tags that others post, if you're planning on submitting your own solution. I have no way to enforce this, but seriously - you won't get much pleasure in being the L19 Go Problem Champion if you cheat to do so.

Without further ado, here are this week's problems. All problems are black to play:

Problem 1 (3 points)

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

Problem 2 (6 points)

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

Problem 3 (9 points)

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

I'll post the solutions prior to posting next week's problems on February 10th. I'll post a weekly leaderboard to maintain a list of who is winning the competition.

Good luck to all participants!

P.S. As much as I'd like to have an L19 awards ceremony, and give prizes to the top participants like I do for my work, I won't be doing that here. For this competition, the only thing you'll receive are bragging rights for being the L19 Go Problem Champion for 2017

EdLee · Post by **EdLee** » Fri Feb 03, 2017 4:33 pm

Kirby, Thanks for doing this.

2017 Round 1.1 (001)

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

2017 Round 1.2 (002)

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

( in progress

... )
If

pushes,

seems forced, otherwise W collapses:

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

Then, if

2nd-line atari, then W lives:

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

If

1st-line atari and

connects, then W dies:

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

Else, ko:

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

2017 Round 1.3 (003)

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

jeromie · Post by **jeromie** » Fri Feb 03, 2017 7:19 pm

This sounds like fun.

Here's an attempt at problem 1:

I'll work on the others as I have time.

gamesorry · Post by **gamesorry** » Fri Feb 03, 2017 11:04 pm

Sounds really fun!

I'll first practice how to use hide-tags...
1. Seki

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

2.

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

Variation (W Fail):

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

Variation 1 (B Fail):

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

Variation 2 (ko, B Fail):

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

Variation 3 (B Fail):

Click Here To Show Diagram Code: [go]$$B $$ ------------------ $$ . . . . . 2 1 8 . | $$ . . X . X O . O . | $$ . . . . X 3 4 6 . | $$ . . . . X O O 5 . | $$ . . . . X X X O 7 | $$ . . . . . . . X . | $$ . . . . . . X . . | $$ . . . . . . . . . | $$ . . . . . . . . . |[/go]

3.
Haven't solved it yet.

I think one way black might kill could be to make the following shape:

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

However, it seems white has some strong resistances, if white makes sure black doesn't get a and b at the same time (so maybe black shouldn't play a/b (which are my intuition) first?.

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

B Fail

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

B Fail

Click Here To Show Diagram Code: [go]$$B $$ ------------------ $$ . . . . . . . 4 8 | $$ . . . X O 7 2 3 5 | $$ . . . X O . 1 O 6 | $$ . . . X . O . . . | $$ . . . . X X X X . | $$ . . . . . . . . . | $$ . . . . . . . X . | $$ . . . . . . . . . | $$ . . . . . . . . . |[/go]

B Fail

Click Here To Show Diagram Code: [go]$$B $$ ------------------ $$ . . . . . . . . . | $$ . . . X O 4 1 3 7 | $$ . . . X O . 2 O 5 | $$ . . . X . O . 8 6 | $$ . . . . X X X X . | $$ . . . . . . . . . | $$ . . . . . . . X . | $$ . . . . . . . . . | $$ . . . . . . . . . |[/go]

Ko

Click Here To Show Diagram Code: [go]$$B $$ ------------------ $$ . . . . 7 8 9 6 . | $$ . . . X O 5 1 3 4 | $$ . . . X O a 2 O . | $$ . . . X . O . . . | $$ . . . . X X X X . | $$ . . . . . . . . . | $$ . . . . . . . X . | $$ . . . . . . . . . | $$ . . . . . . . . . |[/go]

B Fail

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

B Fail

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

B Fail

Click Here To Show Diagram Code: [go]$$B $$ ------------------ $$ . . . . 8 . . . . | $$ . . . X O . 4 6 7 | $$ . . . X O . 1 O 5 | $$ . . . X . O 2 3 . | $$ . . . . X X X X . | $$ . . . . . . . . . | $$ . . . . . . . X . | $$ . . . . . . . . . | $$ . . . . . . . . . |[/go]

B Fail

Click Here To Show Diagram Code: [go]$$B $$ ------------------ $$ . . . . . . . . . | $$ . . . X O . 4 5 . | $$ . . . X O 8 1 O 6 | $$ . . . X . O 2 3 7 | $$ . . . . X X X X . | $$ . . . . . . . . . | $$ . . . . . . . X . | $$ . . . . . . . . . | $$ . . . . . . . . . |[/go]

(Cont'd)

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

Ko

Click Here To Show Diagram Code: [go]$$B $$ ------------------ $$ . . . . . 8 6 7 . | $$ . . . X O . 1 2 9 | $$ . . . X O . 3 O . | $$ . . . X . O 4 5 . | $$ . . . . X X X X . | $$ . . . . . . . . . | $$ . . . . . . . X . | $$ . . . . . . . . . | $$ . . . . . . . . . |[/go]

W2 Fails

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

W4 Fail

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

B Fails

Click Here To Show Diagram Code: [go]$$B $$ ------------------ $$ . . . . . 4 . 6 . | $$ . . . X O 3 1 5 7 | $$ . . . X O . 2 O 8 | $$ . . . X . O . . . | $$ . . . . X X X X . | $$ . . . . . . . . . | $$ . . . . . . . X . | $$ . . . . . . . . . | $$ . . . . . . . . . |[/go]

B Fails

Click Here To Show Diagram Code: [go]$$B $$ ------------------ $$ . . . . 6 4 5 8 . | $$ . . . X O 3 1 7 . | $$ . . . X O . 2 O . | $$ . . . X . O . . . | $$ . . . . X X X X . | $$ . . . . . . . . . | $$ . . . . . . . X . | $$ . . . . . . . . . | $$ . . . . . . . . . |[/go]

Kirby · Post by **Kirby** » Sat Feb 04, 2017 9:25 am

EdLee wrote:Kirby, Thanks for doing this.
001 (3 points)
$$B
$$ -------------------
$$ . . . O X X X O . |
$$ . . . O X . O . . |
$$ . . . O X X X X . |
$$ . . . O O O O O O |
$$ . . . . . . . . . |
Click Here To Show Diagram Code
[go]$$B $$ ------------------- $$ . . . O X X X O . | $$ . . . O X . O . . | $$ . . . O X X X X . | $$ . . . O O O O O O | $$ . . . . . . . . . |[/go]
$$B Seki
$$ -------------------
$$ . . . O X X X O . |
$$ . . . O X . O 2 1 |
$$ . . . O X X X X 3 |
$$ . . . O O O O O O |
$$ . . . . . . . . . |
Click Here To Show Diagram Code
[go]$$B Seki $$ ------------------- $$ . . . O X X X O . | $$ . . . O X . O 2 1 | $$ . . . O X X X X 3 | $$ . . . O O O O O O | $$ . . . . . . . . . |[/go]
$$B var 1 B dies
$$ -------------------
$$ . . . O X X X O 3 |
$$ . . . O X . O 1 2 |
$$ . . . O X X X X 4 |
$$ . . . O O O O O O |
$$ . . . . . . . . . |
Click Here To Show Diagram Code
[go]$$B var 1 B dies $$ ------------------- $$ . . . O X X X O 3 | $$ . . . O X . O 1 2 | $$ . . . O X X X X 4 | $$ . . . O O O O O O | $$ . . . . . . . . . |[/go]
$$B var 2 B dies; :b3: tenuki
$$ -------------------
$$ . . . O X X X O . |
$$ . . . O X . O 4 2 |
$$ . . . O X X X X 1 |
$$ . . . O O O O O O |
$$ . . . . . . . . . |
Click Here To Show Diagram Code
[go]$$B var 2 B dies; :b3: tenuki $$ ------------------- $$ . . . O X X X O . | $$ . . . O X . O 4 2 | $$ . . . O X X X X 1 | $$ . . . O O O O O O | $$ . . . . . . . . . |[/go]
$$B var 3 B dies; reverts to var 1 or 2.
$$ -------------------
$$ . . . O X X X O 1 |
$$ . . . O X . O . 2 |
$$ . . . O X X X X . |
$$ . . . O O O O O O |
$$ . . . . . . . . . |
Click Here To Show Diagram Code
[go]$$B var 3 B dies; reverts to var 1 or 2. $$ ------------------- $$ . . . O X X X O 1 | $$ . . . O X . O . 2 | $$ . . . O X X X X . | $$ . . . O O O O O O | $$ . . . . . . . . . |[/go]
$$B var 4 B dies
$$ -------------------
$$ . . . O X X X O . |
$$ . . . O X 1 O 2 . |
$$ . . . O X X X X . |
$$ . . . O O O O O O |
$$ . . . . . . . . . |
Click Here To Show Diagram Code
[go]$$B var 4 B dies $$ ------------------- $$ . . . O X X X O . | $$ . . . O X 1 O 2 . | $$ . . . O X X X X . | $$ . . . O O O O O O | $$ . . . . . . . . . |[/go]
002 (6 points)
$$B
$$ | . . . . . . . . .
$$ | . X . . . . . . .
$$ | . . . . . . . . .
$$ | . X X X X . . . .
$$ | . O . O X . . . .
$$ | . . . O X . X . .
$$ | . O . . O X . . .
$$ | . . . . . . . . .
$$ -------------------
Click Here To Show Diagram Code
[go]$$B $$ | . . . . . . . . . $$ | . X . . . . . . . $$ | . . . . . . . . . $$ | . X X X X . . . . $$ | . O . O X . . . . $$ | . . . O X . X . . $$ | . O . . O X . . . $$ | . . . . . . . . . $$ -------------------[/go]
( in progress ... )
If pushes, seems forced, otherwise W collapses:
$$B
$$ | . . . . . . . . .
$$ | . X . . . . . . .
$$ | . . . . . . . . .
$$ | . X X X X . . . .
$$ | . O 1 O X . . . .
$$ | . . 2 O X . X . .
$$ | . O . . O X . . .
$$ | . . . . . . . . .
$$ -------------------
Click Here To Show Diagram Code
[go]$$B $$ | . . . . . . . . . $$ | . X . . . . . . . $$ | . . . . . . . . . $$ | . X X X X . . . . $$ | . O 1 O X . . . . $$ | . . 2 O X . X . . $$ | . O . . O X . . . $$ | . . . . . . . . . $$ -------------------[/go]
Then, if 2nd-line atari, then W lives:
$$B W lives
$$ | . . . . . . . . .
$$ | . X . . . . . . .
$$ | . . . . . . . . .
$$ | . X X X X . . . .
$$ | . O 1 O X . . . .
$$ | 6 . 2 O X . X . .
$$ | . O 4 3 O X . . .
$$ | . . . . 5 . . . .
$$ -------------------
Click Here To Show Diagram Code
[go]$$B W lives $$ | . . . . . . . . . $$ | . X . . . . . . . $$ | . . . . . . . . . $$ | . X X X X . . . . $$ | . O 1 O X . . . . $$ | 6 . 2 O X . X . . $$ | . O 4 3 O X . . . $$ | . . . . 5 . . . . $$ -------------------[/go]
If 1st-line atari and connects, then W dies:
$$B W dies (but...)
$$ | . . . . . . . . .
$$ | . X . . . . . . .
$$ | . . . . . . . . .
$$ | . X X X X . . . .
$$ | 3 O 1 O X . . . .
$$ | . 4 2 O X . X . .
$$ | . O 6 5 O X . . .
$$ | . . . . 7 . . . .
$$ -------------------
Click Here To Show Diagram Code
[go]$$B W dies (but...) $$ | . . . . . . . . . $$ | . X . . . . . . . $$ | . . . . . . . . . $$ | . X X X X . . . . $$ | 3 O 1 O X . . . . $$ | . 4 2 O X . X . . $$ | . O 6 5 O X . . . $$ | . . . . 7 . . . . $$ -------------------[/go]
Else, ko:
$$B ko
$$ | . . . . . . . . .
$$ | . X . . . . . . .
$$ | . . . . . . . . .
$$ | . X X X X . . . .
$$ | 3 O 1 O X . . . .
$$ | 4 5 2 O X . X . .
$$ | . O . . O X . . .
$$ | . . . . . . . . .
$$ -------------------
Click Here To Show Diagram Code
[go]$$B ko $$ | . . . . . . . . . $$ | . X . . . . . . . $$ | . . . . . . . . . $$ | . X X X X . . . . $$ | 3 O 1 O X . . . . $$ | 4 5 2 O X . X . . $$ | . O . . O X . . . $$ | . . . . . . . . . $$ -------------------[/go]
003 (9 points)
$$B
$$ | . . . . . . . . .
$$ | . X X X . . . . .
$$ | . O O . X . . . .
$$ | . . . O X . . . .
$$ | . . . . X . . . .
$$ | . . O . X . X . .
$$ | . . . . . . . . .
$$ -------------------
Click Here To Show Diagram Code
[go]$$B $$ | . . . . . . . . . $$ | . X X X . . . . . $$ | . O O . X . . . . $$ | . . . O X . . . . $$ | . . . . X . . . . $$ | . . O . X . X . . $$ | . . . . . . . . . $$ -------------------[/go]
( ... )
Random first feeling
$$B
$$ | . . . . . . . . .
$$ | . X X X . . . . .
$$ | . O O . X . . . .
$$ | . . . O X . . . .
$$ | . . 1 . X . . . .
$$ | . . O . X . X . .
$$ | . . . . . . . . .
$$ -------------------
Click Here To Show Diagram Code
[go]$$B $$ | . . . . . . . . . $$ | . X X X . . . . . $$ | . O O . X . . . . $$ | . . . O X . . . . $$ | . . 1 . X . . . . $$ | . . O . X . X . . $$ | . . . . . . . . . $$ -------------------[/go]

@EdLee:

Kirby · Post by **Kirby** » Sat Feb 04, 2017 9:26 am

jeromie wrote:This sounds like fun.

Here's an attempt at problem 1:
I think the best result is seki:
$$B
$$ ------------------
$$ . . . O X X X O . |
$$ . . . O X . O 2 1 |
$$ . . . O X X X X 3 |
$$ . . . O O O O O O |
$$ . . . . . . . . . |
$$ . . . . . . . . . |
$$ . . . . . . . . . |
$$ . . . . . . . . . |
$$ . . . . . . . . . |
Click Here To Show Diagram Code
[go]$$B $$ ------------------ $$ . . . O X X X O . | $$ . . . O X . O 2 1 | $$ . . . O X X X X 3 | $$ . . . O O O O O O | $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . . . . . . |[/go]
I'll work on the others as I have time.

@jeromie:

Kirby · Post by **Kirby** » Sat Feb 04, 2017 9:35 am

gamesorry wrote:Sounds really fun!
I'll first practice how to use hide-tags...
1. Seki
$$B
$$ ------------------
$$ . . . O X X X O . |
$$ . . . O X . O 2 1 |
$$ . . . O X X X X 3 |
$$ . . . O O O O O O |
$$ . . . . . . . . . |
$$ . . . . . . . . . |
$$ . . . . . . . . . |
$$ . . . . . . . . . |
$$ . . . . . . . . . |
Click Here To Show Diagram Code
[go]$$B $$ ------------------ $$ . . . O X X X O . | $$ . . . O X . O 2 1 | $$ . . . O X X X X 3 | $$ . . . O O O O O O | $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . . . . . . |[/go]
2.

$$B
$$ ------------------
$$ . . . . . 1 2 . . |
$$ . . X . X O 7 O . |
$$ . . . . X 5 3 4 . |
$$ . . . . X O O 6 . |
$$ . . . . X X X O . |
$$ . . . . . . . X . |
$$ . . . . . . X . . |
$$ . . . . . . . . . |
$$ . . . . . . . . . |
Click Here To Show Diagram Code
[go]$$B $$ ------------------ $$ . . . . . 1 2 . . | $$ . . X . X O 7 O . | $$ . . . . X 5 3 4 . | $$ . . . . X O O 6 . | $$ . . . . X X X O . | $$ . . . . . . . X . | $$ . . . . . . X . . | $$ . . . . . . . . . | $$ . . . . . . . . . |[/go]
Variation (W Fail):
$$B
$$ ------------------
$$ . . . . . 1 2 . . |
$$ . . X . X O 6 O . |
$$ . . . . X 4 3 7 . |
$$ . . . . X O O 5 . |
$$ . . . . X X X O . |
$$ . . . . . . . X . |
$$ . . . . . . X . . |
$$ . . . . . . . . . |
$$ . . . . . . . . . |
Click Here To Show Diagram Code
[go]$$B $$ ------------------ $$ . . . . . 1 2 . . | $$ . . X . X O 6 O . | $$ . . . . X 4 3 7 . | $$ . . . . X O O 5 . | $$ . . . . X X X O . | $$ . . . . . . . X . | $$ . . . . . . X . . | $$ . . . . . . . . . | $$ . . . . . . . . . |[/go]
Variation 1 (B Fail):
$$B
$$ ------------------
$$ . . . . . . . . . |
$$ . . X . X O . O . |
$$ . . . . X 4 . 2 . |
$$ . . . . X O O 1 . |
$$ . . . . X X X O 3 |
$$ . . . . . . . X . |
$$ . . . . . . X . . |
$$ . . . . . . . . . |
$$ . . . . . . . . . |
Click Here To Show Diagram Code
[go]$$B $$ ------------------ $$ . . . . . . . . . | $$ . . X . X O . O . | $$ . . . . X 4 . 2 . | $$ . . . . X O O 1 . | $$ . . . . X X X O 3 | $$ . . . . . . . X . | $$ . . . . . . X . . | $$ . . . . . . . . . | $$ . . . . . . . . . |[/go]
Variation 2 (ko, B Fail):
$$B
$$ ------------------
$$ . . . . . 3 4 . . |
$$ . . X . X O . O . |
$$ . . . . X 1 2 . . |
$$ . . . . X O O . . |
$$ . . . . X X X O . |
$$ . . . . . . . X . |
$$ . . . . . . X . . |
$$ . . . . . . . . . |
$$ . . . . . . . . . |
Click Here To Show Diagram Code
[go]$$B $$ ------------------ $$ . . . . . 3 4 . . | $$ . . X . X O . O . | $$ . . . . X 1 2 . . | $$ . . . . X O O . . | $$ . . . . X X X O . | $$ . . . . . . . X . | $$ . . . . . . X . . | $$ . . . . . . . . . | $$ . . . . . . . . . |[/go]
Variation 3 (B Fail):
$$B
$$ ------------------
$$ . . . . . 2 1 8 . |
$$ . . X . X O . O . |
$$ . . . . X 3 4 6 . |
$$ . . . . X O O 5 . |
$$ . . . . X X X O 7 |
$$ . . . . . . . X . |
$$ . . . . . . X . . |
$$ . . . . . . . . . |
$$ . . . . . . . . . |
Click Here To Show Diagram Code
[go]$$B $$ ------------------ $$ . . . . . 2 1 8 . | $$ . . X . X O . O . | $$ . . . . X 3 4 6 . | $$ . . . . X O O 5 . | $$ . . . . X X X O 7 | $$ . . . . . . . X . | $$ . . . . . . X . . | $$ . . . . . . . . . | $$ . . . . . . . . . |[/go]
3.
Haven't solved it yet.

I think one way black might kill could be to make the following shape:
$$B
$$ ------------------
$$ . . . . O X . . . |
$$ . . . X O . X O . |
$$ . . . X O . X O . |
$$ . . . X . O O X . |
$$ . . . . X X X X . |
$$ . . . . . . . . . |
$$ . . . . . . . X . |
$$ . . . . . . . . . |
$$ . . . . . . . . . |
Click Here To Show Diagram Code
[go]$$B $$ ------------------ $$ . . . . O X . . . | $$ . . . X O . X O . | $$ . . . X O . X O . | $$ . . . X . O O X . | $$ . . . . X X X X . | $$ . . . . . . . . . | $$ . . . . . . . X . | $$ . . . . . . . . . | $$ . . . . . . . . . |[/go]
However, it seems white has some strong resistances, if white makes sure black doesn't get a and b at the same time (so maybe black shouldn't play a/b (which are my intuition) first?.

$$B
$$ ------------------
$$ . . . . . . . . . |
$$ . . . X O . a . . |
$$ . . . X O . b O . |
$$ . . . X . O . . . |
$$ . . . . X X X X . |
$$ . . . . . . . . . |
$$ . . . . . . . X . |
$$ . . . . . . . . . |
$$ . . . . . . . . . |
Click Here To Show Diagram Code
[go]$$B $$ ------------------ $$ . . . . . . . . . | $$ . . . X O . a . . | $$ . . . X O . b O . | $$ . . . X . O . . . | $$ . . . . X X X X . | $$ . . . . . . . . . | $$ . . . . . . . X . | $$ . . . . . . . . . | $$ . . . . . . . . . |[/go]
B Fail
$$B
$$ ------------------
$$ . . . . . . . 4 . |
$$ . . . X O . 2 . . |
$$ . . . X O . 1 O . |
$$ . . . X . O 3 . . |
$$ . . . . X X X X . |
$$ . . . . . . . . . |
$$ . . . . . . . X . |
$$ . . . . . . . . . |
$$ . . . . . . . . . |
Click Here To Show Diagram Code
[go]$$B $$ ------------------ $$ . . . . . . . 4 . | $$ . . . X O . 2 . . | $$ . . . X O . 1 O . | $$ . . . X . O 3 . . | $$ . . . . X X X X . | $$ . . . . . . . . . | $$ . . . . . . . X . | $$ . . . . . . . . . | $$ . . . . . . . . . |[/go]
B Fail
$$B
$$ ------------------
$$ . . . . . . . 4 8 |
$$ . . . X O 7 2 3 5 |
$$ . . . X O . 1 O 6 |
$$ . . . X . O . . . |
$$ . . . . X X X X . |
$$ . . . . . . . . . |
$$ . . . . . . . X . |
$$ . . . . . . . . . |
$$ . . . . . . . . . |
Click Here To Show Diagram Code
[go]$$B $$ ------------------ $$ . . . . . . . 4 8 | $$ . . . X O 7 2 3 5 | $$ . . . X O . 1 O 6 | $$ . . . X . O . . . | $$ . . . . X X X X . | $$ . . . . . . . . . | $$ . . . . . . . X . | $$ . . . . . . . . . | $$ . . . . . . . . . |[/go]
B Fail
$$B
$$ ------------------
$$ . . . . . . . . . |
$$ . . . X O 4 1 3 7 |
$$ . . . X O . 2 O 5 |
$$ . . . X . O . 8 6 |
$$ . . . . X X X X . |
$$ . . . . . . . . . |
$$ . . . . . . . X . |
$$ . . . . . . . . . |
$$ . . . . . . . . . |
Click Here To Show Diagram Code
[go]$$B $$ ------------------ $$ . . . . . . . . . | $$ . . . X O 4 1 3 7 | $$ . . . X O . 2 O 5 | $$ . . . X . O . 8 6 | $$ . . . . X X X X . | $$ . . . . . . . . . | $$ . . . . . . . X . | $$ . . . . . . . . . | $$ . . . . . . . . . |[/go]
Ko
$$B
$$ ------------------
$$ . . . . 7 8 9 6 . |
$$ . . . X O 5 1 3 4 |
$$ . . . X O a 2 O . |
$$ . . . X . O . . . |
$$ . . . . X X X X . |
$$ . . . . . . . . . |
$$ . . . . . . . X . |
$$ . . . . . . . . . |
$$ . . . . . . . . . |
Click Here To Show Diagram Code
[go]$$B $$ ------------------ $$ . . . . 7 8 9 6 . | $$ . . . X O 5 1 3 4 | $$ . . . X O a 2 O . | $$ . . . X . O . . . | $$ . . . . X X X X . | $$ . . . . . . . . . | $$ . . . . . . . X . | $$ . . . . . . . . . | $$ . . . . . . . . . |[/go]
B Fail
$$B
$$ ------------------
$$ . . . . . 5 . . . |
$$ . . . X O 6 1 3 4 |
$$ . . . X O . 2 O . |
$$ . . . X . O . . . |
$$ . . . . X X X X . |
$$ . . . . . . . . . |
$$ . . . . . . . X . |
$$ . . . . . . . . . |
$$ . . . . . . . . . |
Click Here To Show Diagram Code
[go]$$B $$ ------------------ $$ . . . . . 5 . . . | $$ . . . X O 6 1 3 4 | $$ . . . X O . 2 O . | $$ . . . X . O . . . | $$ . . . . X X X X . | $$ . . . . . . . . . | $$ . . . . . . . X . | $$ . . . . . . . . . | $$ . . . . . . . . . |[/go]
B Fail
$$B
$$ ------------------
$$ . . . . 6 . . . . |
$$ . . . X O 5 . 3 . |
$$ . . . X O . 1 O . |
$$ . . . X . O 2 4 . |
$$ . . . . X X X X . |
$$ . . . . . . . . . |
$$ . . . . . . . X . |
$$ . . . . . . . . . |
$$ . . . . . . . . . |
Click Here To Show Diagram Code
[go]$$B $$ ------------------ $$ . . . . 6 . . . . | $$ . . . X O 5 . 3 . | $$ . . . X O . 1 O . | $$ . . . X . O 2 4 . | $$ . . . . X X X X . | $$ . . . . . . . . . | $$ . . . . . . . X . | $$ . . . . . . . . . | $$ . . . . . . . . . |[/go]
B Fail
$$B
$$ ------------------
$$ . . . . 8 . . . . |
$$ . . . X O . 4 6 7 |
$$ . . . X O . 1 O 5 |
$$ . . . X . O 2 3 . |
$$ . . . . X X X X . |
$$ . . . . . . . . . |
$$ . . . . . . . X . |
$$ . . . . . . . . . |
$$ . . . . . . . . . |
Click Here To Show Diagram Code
[go]$$B $$ ------------------ $$ . . . . 8 . . . . | $$ . . . X O . 4 6 7 | $$ . . . X O . 1 O 5 | $$ . . . X . O 2 3 . | $$ . . . . X X X X . | $$ . . . . . . . . . | $$ . . . . . . . X . | $$ . . . . . . . . . | $$ . . . . . . . . . |[/go]
B Fail
$$B
$$ ------------------
$$ . . . . . . . . . |
$$ . . . X O . 4 5 . |
$$ . . . X O 8 1 O 6 |
$$ . . . X . O 2 3 7 |
$$ . . . . X X X X . |
$$ . . . . . . . . . |
$$ . . . . . . . X . |
$$ . . . . . . . . . |
$$ . . . . . . . . . |
Click Here To Show Diagram Code
[go]$$B $$ ------------------ $$ . . . . . . . . . | $$ . . . X O . 4 5 . | $$ . . . X O 8 1 O 6 | $$ . . . X . O 2 3 7 | $$ . . . . X X X X . | $$ . . . . . . . . . | $$ . . . . . . . X . | $$ . . . . . . . . . | $$ . . . . . . . . . |[/go]
(Cont'd)

$$B
$$ ------------------
$$ . . . . 4 3 5 6 . |
$$ . . . X O . O X 1 |
$$ . . . X O O 2 O O |
$$ . . . X . O O X X |
$$ . . . . X X X X . |
$$ . . . . . . . . . |
$$ . . . . . . . X . |
$$ . . . . . . . . . |
$$ . . . . . . . . . |
Click Here To Show Diagram Code
[go]$$B $$ ------------------ $$ . . . . 4 3 5 6 . | $$ . . . X O . O X 1 | $$ . . . X O O 2 O O | $$ . . . X . O O X X | $$ . . . . X X X X . | $$ . . . . . . . . . | $$ . . . . . . . X . | $$ . . . . . . . . . | $$ . . . . . . . . . |[/go]
Ko
$$B
$$ ------------------
$$ . . . . . 8 6 7 . |
$$ . . . X O . 1 2 9 |
$$ . . . X O . 3 O . |
$$ . . . X . O 4 5 . |
$$ . . . . X X X X . |
$$ . . . . . . . . . |
$$ . . . . . . . X . |
$$ . . . . . . . . . |
$$ . . . . . . . . . |
Click Here To Show Diagram Code
[go]$$B $$ ------------------ $$ . . . . . 8 6 7 . | $$ . . . X O . 1 2 9 | $$ . . . X O . 3 O . | $$ . . . X . O 4 5 . | $$ . . . . X X X X . | $$ . . . . . . . . . | $$ . . . . . . . X . | $$ . . . . . . . . . | $$ . . . . . . . . . |[/go]
W2 Fails
$$B
$$ ------------------
$$ . . . . 6 5 . . . |
$$ . . . X O . 1 2 . |
$$ . . . X O . 3 O . |
$$ . . . X . O 4 7 . |
$$ . . . . X X X X . |
$$ . . . . . . . . . |
$$ . . . . . . . X . |
$$ . . . . . . . . . |
$$ . . . . . . . . . |
Click Here To Show Diagram Code
[go]$$B $$ ------------------ $$ . . . . 6 5 . . . | $$ . . . X O . 1 2 . | $$ . . . X O . 3 O . | $$ . . . X . O 4 7 . | $$ . . . . X X X X . | $$ . . . . . . . . . | $$ . . . . . . . X . | $$ . . . . . . . . . | $$ . . . . . . . . . |[/go]
W4 Fail
$$B
$$ ------------------
$$ . . . . 4 . . . . |
$$ . . . X O 3 1 . . |
$$ . . . X O 5 2 O . |
$$ . . . X . O . . . |
$$ . . . . X X X X . |
$$ . . . . . . . . . |
$$ . . . . . . . X . |
$$ . . . . . . . . . |
$$ . . . . . . . . . |
Click Here To Show Diagram Code
[go]$$B $$ ------------------ $$ . . . . 4 . . . . | $$ . . . X O 3 1 . . | $$ . . . X O 5 2 O . | $$ . . . X . O . . . | $$ . . . . X X X X . | $$ . . . . . . . . . | $$ . . . . . . . X . | $$ . . . . . . . . . | $$ . . . . . . . . . |[/go]
B Fails
$$B
$$ ------------------
$$ . . . . . 4 . 6 . |
$$ . . . X O 3 1 5 7 |
$$ . . . X O . 2 O 8 |
$$ . . . X . O . . . |
$$ . . . . X X X X . |
$$ . . . . . . . . . |
$$ . . . . . . . X . |
$$ . . . . . . . . . |
$$ . . . . . . . . . |
Click Here To Show Diagram Code
[go]$$B $$ ------------------ $$ . . . . . 4 . 6 . | $$ . . . X O 3 1 5 7 | $$ . . . X O . 2 O 8 | $$ . . . X . O . . . | $$ . . . . X X X X . | $$ . . . . . . . . . | $$ . . . . . . . X . | $$ . . . . . . . . . | $$ . . . . . . . . . |[/go]
B Fails
$$B
$$ ------------------
$$ . . . . 6 4 5 8 . |
$$ . . . X O 3 1 7 . |
$$ . . . X O . 2 O . |
$$ . . . X . O . . . |
$$ . . . . X X X X . |
$$ . . . . . . . . . |
$$ . . . . . . . X . |
$$ . . . . . . . . . |
$$ . . . . . . . . . |
Click Here To Show Diagram Code
[go]$$B $$ ------------------ $$ . . . . 6 4 5 8 . | $$ . . . X O 3 1 7 . | $$ . . . X O . 2 O . | $$ . . . X . O . . . | $$ . . . . X X X X . | $$ . . . . . . . . . | $$ . . . . . . . X . | $$ . . . . . . . . . | $$ . . . . . . . . . |[/go]

@gamesorry:

gamesorry · Post by **gamesorry** » Mon Feb 06, 2017 12:24 am

@Kirby Thank you

Kirby wrote: @gamesorry:
Problem 3: Nice thorough solution! I should note that ko is a possible solution for a problem. That being said, is this diagram really a failure?

B Fails
$$B
$$ ------------------
$$ . . . . 6 4 5 8 . |
$$ . . . X O 3 1 7 . |
$$ . . . X O . 2 O . |
$$ . . . X . O . . . |
$$ . . . . X X X X . |
$$ . . . . . . . . . |
$$ . . . . . . . X . |
$$ . . . . . . . . . |
$$ . . . . . . . . . |
Click Here To Show Diagram Code
[go]$$B $$ ------------------ $$ . . . . 6 4 5 8 . | $$ . . . X O 3 1 7 . | $$ . . . X O . 2 O . | $$ . . . X . O . . . | $$ . . . . X X X X . | $$ . . . . . . . . . | $$ . . . . . . . X . | $$ . . . . . . . . . | $$ . . . . . . . . . |[/go]
Does black have a continuation?

Ah, Black can make a one-move (or even more?) approach ko (yose ko)

Click Here To Show Diagram Code: [go]$$B $$ ------------------ $$ . . . 5 O O X O 3 | $$ . . . X O X X X 8 | $$ . . . X O 6 O O 1 | $$ . . . X 7 O . 4 2 | $$ . . . . X X X X . | $$ . . . . . . . . . | $$ . . . . . . . X . | $$ . . . . . . . . . | $$ . . . . . . . . . |[/go]

I guess that is the best answer I could find for B for now ...

So if the goal is for B to make a ko, then the following one is not a failure for B but for W:

Click Here To Show Diagram Code: [go]$$B $$ ------------------ $$ . . . . 9 a . 4 8 | $$ . . . X O 7 2 3 5 | $$ . . . X O . 1 O 6 | $$ . . . X . O . . . | $$ . . . . X X X X . | $$ . . . . . . . . . | $$ . . . . . . . X . | $$ . . . . . . . . . | $$ . . . . . . . . . |[/go]

However, W can play the other way:

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

Kirby · Post by **Kirby** » Mon Feb 06, 2017 12:45 am

gamesorry wrote:@Kirby Thank you
Kirby wrote: @gamesorry:
Problem 3: Nice thorough solution! I should note that ko is a possible solution for a problem. That being said, is this diagram really a failure?

B Fails
$$B
$$ ------------------
$$ . . . . 6 4 5 8 . |
$$ . . . X O 3 1 7 . |
$$ . . . X O . 2 O . |
$$ . . . X . O . . . |
$$ . . . . X X X X . |
$$ . . . . . . . . . |
$$ . . . . . . . X . |
$$ . . . . . . . . . |
$$ . . . . . . . . . |
Click Here To Show Diagram Code
[go]$$B $$ ------------------ $$ . . . . 6 4 5 8 . | $$ . . . X O 3 1 7 . | $$ . . . X O . 2 O . | $$ . . . X . O . . . | $$ . . . . X X X X . | $$ . . . . . . . . . | $$ . . . . . . . X . | $$ . . . . . . . . . | $$ . . . . . . . . . |[/go]
Does black have a continuation?
Ah, Black can make a one-move (or even more?) approach ko (yose ko)
$$B
$$ ------------------
$$ . . . 5 O O X O 3 |
$$ . . . X O X X X 8 |
$$ . . . X O 6 O O 1 |
$$ . . . X 7 O . 4 2 |
$$ . . . . X X X X . |
$$ . . . . . . . . . |
$$ . . . . . . . X . |
$$ . . . . . . . . . |
$$ . . . . . . . . . |
Click Here To Show Diagram Code
[go]$$B $$ ------------------ $$ . . . 5 O O X O 3 | $$ . . . X O X X X 8 | $$ . . . X O 6 O O 1 | $$ . . . X 7 O . 4 2 | $$ . . . . X X X X . | $$ . . . . . . . . . | $$ . . . . . . . X . | $$ . . . . . . . . . | $$ . . . . . . . . . |[/go]
I guess this is the best answer I could find so far ...

Lanrose · Post by **Lanrose** » Tue Feb 21, 2017 8:28 am

Now that things seem to be working again I hope that you continue with this competition Kirby. After not playing for almost a year I realize how my reading skills have deteriorated.

Here's the first one

I'm hoping to be able to solve the next two when I have time but at this point I'm not sure I'll be able to solve them.

Kirby · Post by **Kirby** » Tue Feb 21, 2017 8:58 am

I'll aim to post the solutions and next set of problems on Friday. We got out of sync with the L19 outage, and I like to have the boundary on an easy-to-remember day like Friday.

Kirby · Post by **Kirby** » Tue Feb 21, 2017 9:34 pm

Lanrose wrote:Now that things seem to be working again I hope that you continue with this competition Kirby. After not playing for almost a year I realize how my reading skills have deteriorated.

Here's the first one

$$B
$$ ------------------
$$ . . . O X X X O . |
$$ . . . O X . O 2 1 |
$$ . . . O X X X X 3 |
$$ . . . O O O O O O |
$$ . . . . . . . . . |
$$ . . . . . . . . . |
$$ . . . . . . . . . |
$$ . . . . . . . . . |
$$ . . . . . . . . . |
Click Here To Show Diagram Code
[go]$$B $$ ------------------ $$ . . . O X X X O . | $$ . . . O X . O 2 1 | $$ . . . O X X X X 3 | $$ . . . O O O O O O | $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . . . . . . | $$ . . . . . . . . . |[/go]
I'm hoping to be able to solve the next two when I have time but at this point I'm not sure I'll be able to solve them.

@Lanrose:

Kirby · Post by **Kirby** » Thu Feb 23, 2017 10:45 pm

Thanks to all who participated in Round 1 of the L19 Go Problem Championship!

Solutions and an updated leader board are given below.

Problem 1:

Problem 2:

Problem 3:

Leaderboard
1. gamesorry - 18
2. Schachus - 9
3. EdLee - 5
4. jeromie, dfan, Lanrose - 3

EdLee · Post by **EdLee** » Fri Feb 24, 2017 4:31 pm

Click Here To Show Diagram Code: [go]$$B 002. $$ | . . . . . . . . . $$ | . X . . . . . . . $$ | . . . . . . . . . $$ | . X X X X . . . . $$ | 1 O . O X . . . . $$ | a . . O X . X . . $$ | . O . . O X . . . $$ | . . . . . . . . . $$ -------------------[/go]

Hi Kirby, Thanks. After

hane, W has ~12 local

's --
the hane-atari (a) is only one of them. The tree is still quite big. Thanks.

Kirby · Post by **Kirby** » Fri Feb 24, 2017 4:46 pm

I agree. I could have added detail in the variations here.

Life In 19x19

L19 Go Problem Championship: Round 1

L19 Go Problem Championship: Round 1

Re: L19 Go Problem Championship: Round 1

Re: L19 Go Problem Championship: Round 1

Re: L19 Go Problem Championship: Round 1

Re: L19 Go Problem Championship: Round 1

Re: L19 Go Problem Championship: Round 1

Re: L19 Go Problem Championship: Round 1

Re: L19 Go Problem Championship: Round 1

Re: L19 Go Problem Championship: Round 1

Re: L19 Go Problem Championship: Round 1

Re: L19 Go Problem Championship: Round 1

Re: L19 Go Problem Championship: Round 1

Re: L19 Go Problem Championship: Round 1