This is the 15x15 game I just played against the computer...I was black.

Click Here To Show Diagram Code

[go]$$ ---------------------------------
$$ | . . . . .X O O . O O X O . . |
$$ | . . . . . . X O . O X X O O O |
$$ | . . . . X X X X O . O X X X X |
$$ | . X X . X O O O . . O O X . O |
$$ | X . . . X X O . O . O X X X X |
$$ | O X X . . X O . . . . O O X X |
$$ | O O O X X X O . . . . . . O X |
$$ | . . O X X O . . . . . . O . O |
$$ | . . . O O . . . . . . . . X . |
$$ | . . O O O O O O O O . O . . . |
$$ | . O X X X X O X O X O . O . . |
$$ | . O X X X O O X X X X O O O O |
$$ | . . O X . X X . X X . X X X O |
$$ | . . O X . X . . . . . . . X X |
$$ | . . O O X . . . . , . . . . . |
$$ -------------------------------[/go]

Just thought it was of interest because, in spite of having two solid eyes, the black shape in the upper right corner is dead anyway. Didn't know that could happen.

Grr....

Hmm, there's no solid eyes there, unfortunately. That entire group only has one liberty, and when you take that solitary white stone, you'll still only have one liberty left...white then follows up with a single move to kill your group, as it can take that final liberty.

If that white group in the upper most right corner (surrounded by your black stones) had less liberties than the black group surrounding it, you'd be in a better position and should be able to live. Because it has two liberties though, and you only have one, your group is unfortunately dead.

Hope that makes sense! (And apologies if I'm telling you something you already know!)

_________________

No in terms of eyes there's two eyes there as I understand the concept of eyes - not false eyes, if you took away the white stones inside it we'd say it was alive. It's just that Inkwolf assumed two eyes = unconditional life how ever many stones white plays inside and let the computer get an eye inside his big eye etc. btw Richard Hunter's Counting liberties, or his chapters in the 2nd book of Go would be the place to read a bit about this sort of thing.

_________________
I am John. John-I-Am.

Ahh, I see your point. My understanding of a double eye structure is one which is stable, rather than having the potential to be settled into two eyes. I don't know if there's a difference in terminology I'm not familiar with, but, that was the interpretation I was basing my explanation from.

_________________

A better way to think about it: there's a group with one eye in a capture race vs another group with one eye. If you have "The second book of Go", it has a few chapters explaining how to read these fights out (definitely worth a read. It was a really enlightening moment when I understood how these sorts of fights work).

If we collapse white's eye, it's a different type of fight altogether. In this case, no matter how many free moves white gets, he can't capture that black group.

Click Here To Show Diagram Code

[go]Bc
$$ ---------------------------------
$$ | . . . . . X O O . O O X . O O |
$$ | . . . . . . X O . O X X O O O |
$$ | . . . . X X X X O . O X X X X |
$$ | . X X . X O O O . . O O X . O |
$$ | X . . . X X O . O . O X X X X |
$$ | O X X . . X O . . . . O O X X |
$$ | O O O X X X O . . . . . . O X |
$$ | . . O X X O . . . . . . O . O |
$$ | . . . O O . . . . . . . . X . |
$$ | . . O O O O O O O O . O . . . |
$$ | . O X X X X O X O X O . O . . |
$$ | . O X X X O O X X X X O O O O |
$$ | . . O X . X X . X X . X X X O |
$$ | . . O X . X . . . . . . . X X |
$$ | . . O O X . . . . , . . . . . |
$$ -------------------------------[/go]

This is even more fun:

Click Here To Show Diagram Code

[go]$$ Status?
$$ ---------------------------------
$$ | . . . . . X O O . O O X . O . |
$$ | . . . . . . X O . O X X O O O |
$$ | . . . . X X X X O . O X X X X |
$$ | . X X . X O O O . . O O X . O |
$$ | X . . . X X O . O . O X X X X |
$$ | O X X . . X O . . . . O O X X |
$$ | O O O X X X O . . . . . . O X |
$$ | . . O X X O . . . . . . O . O |
$$ | . . . O O . . . . . . . . X . |
$$ | . . O O O O O O O O . O . . . |
$$ | . O X X X X O X O X O . O . . |
$$ | . O X X X O O X X X X O O O O |
$$ | . . O X . X X . X X . X X X O |
$$ | . . O X . X . . . . . . . X X |
$$ | . . O O X . . . . , . . . . . |
$$ -------------------------------[/go]

_________________
1k KGS

Oh yes, thanks.

Click Here To Show Diagram Code

[go]$$ Status?
$$ ---------------------------------
$$ | . . . . . X O O . O O X . O . |
$$ | . . . . . . X O . O X X O O O |
$$ | . . . . X X X X O . O X X X X |
$$ | . X X . X O O O . . O O X . O |
$$ | X . . . X X O . O . O X X X X |
$$ | O X X . . X O . . . . O O X X |
$$ | O O O X X X O . . . . . . O X |
$$ | . . O X X O . . . . . . O . O |
$$ | . . . O O . . . . . . . . X . |
$$ | . . O O O O O O O O . O . . . |
$$ | . O X X X X O X O X O . O . . |
$$ | . O X X X O O X X X X O O O O |
$$ | . . O X . X X . X X . X X X O |
$$ | . . O X . X . . . . . . . X X |
$$ | . . O O X . . . . , . . . . . |
$$ -------------------------------[/go]

Neither black or white can make take the final, shared liberty, so

either a seki or black can squash white with:

Click Here To Show Diagram Code

[go]$$ black gets territory
$$ ---------------------------------
$$ | . . . . . X O O . O O X . O . |
$$ | . . . . . . X O . O X X O O O |
$$ | . . . . X X X X O . O X X X X |
$$ | . X X . X O O O . . O O X . O |
$$ | X . . . X X O . O . O X X X X |
$$ | O X X . . X O . . . . O O X X |
$$ | O O O X X X O . . . . . . O X |
$$ | . . O X X O . . . . . . O X O |
$$ | . . . O O . . . . . . . . X . |
$$ | . . O O O O O O O O . O . . . |
$$ | . O X X X X O X O X O . O . . |
$$ | . O X X X O O X X X X O O O O |
$$ | . . O X . X X . X X . X X X O |
$$ | . . O X . X . . . . . . . X X |
$$ | . . O O X . . . . , . . . . . |
$$ -------------------------------[/go]

and seki if white plays there. ?

_________________
I am John. John-I-Am.

Interesting debate. To me, this is just (as others have already said) a capturing race between two groups with 1 eye (and one which black is losing, just).

It might conceivably have arisen from a position in which black did have two solid eyes, but if so, they needed to not let white get so many plays in. In particular, letting your opponent make an eye of their own inside your eye (which, in practice, seems to only ever happen in the corner, although in theory it can happen in any large enough space) makes it to all intents and purposes not an eye anymore. Easy game, go

(This sensei's page has some related material:http://senseis.xmp.net/?path=EyesCollection&page=EyeInTheBelly - although in those examples white has no other eyes, so it's an eye-versus-no-eye capturing race, not an eye-vs-eye one as in your example.)

Good lesson for you, Inkwolf. If you post the entire game here,
maybe people can figure out your mistake(s) that corner.

Yes, it was a good lesson. One I'm glad I got from the computer instead of another person, because I might have called them the same names I called the computer...

The game is probably too full of mistakes for anyone to narrow down just one spot where it went wrong. But if you really want to look, here's the SGF:
http://home.earthlink.net/~inkwolf/TheAnnoyingDead.sgf

The game as it ends there is just before I moved into the tiger's mouth from the peep at 07, and the computer made my entire formation disappear. (I hit 'undo' to figure out just what the heck had happened.)

Click Here To Show Diagram Code

[go]$$W
$$ ---------------------------------
$$ | . . . . . X O O . O O X 1 2 . |
$$ | . . . . . . X O . O X X . O O |
$$ | . . . . X X X X O . O X X X X |
$$ | . X X . X O O O . . O O X . O |
$$ | X . . . X X O . O . O X X X X |
$$ | O X X . . X O . . . . O O X X |
$$ | O O O X X X O . . . . . . O X |
$$ | . . O X X O . . . . . . O . O |
$$ | . . . O O . . . . . . . . X . |
$$ | . . O O O O O O O O . O . . . |
$$ | . O X X X X O X O X O . O . . |
$$ | . O X X X O O X X X X O O O O |
$$ | . . O X . X X . X X . X X X O |
$$ | . . O X . X . . . . . . . X X |
$$ | . . O O X . . . . , . . . . . |
$$ -------------------------------[/go]

If this happened because white played , you need to play to stay alive (white will capture, and then it is a seki). Ideally, you would have responded to an earlier white move. If the other player can make his own eye inside your eye, then it's not really your eye.

_________________
That which can be destroyed by the truth should be.
--
My (sadly neglected, but not forgotten) project: http://dailyjoseki.com

A few shape problems:
(The SGF is correct, at 15x15, but I don't know how to tell the inline editor )
[sgf-full](;CA[utf-8]RU[Japanese]FF[4]AP[Goban:3.2.12]SZ[15]GM[1]DT[2011-05-16]PB[Colette Bezio]
BR[NR]PW[GNU Go]WR[NR]KM[6.5]HA[0]RE[W+53.5]US[Colette Bezio]MULTIGOGM[0]
;B[dl];W[cj];B[fm];W[bl];B[im];W[ej];B[lm];W[mk];B[nm];W[mh];B[me];W[kd];B[lc];W[kc]
(;B[kb]C[See var.];W[jb];B[lb];W[ic];B[ec];W[lf];B[cd];W[cg];B[cf];W[bg];B[bf];W[cm]
;B[gc];W[ie];B[dm];W[cn];B[dn];W[mf]
(;B[nf]LB[kb:a]C[This is the second time you make this shape -- first was (a). See var.]
;W[ng]
(;B[oe]C[Bad habit. See var.];W[gd];B[le];W[ke];B[hc];W[fd];B[fc];W[hj];B[hk];W[jj]
;B[jk];W[kk];B[kl];W[ll];B[jm];W[ik];B[jl];W[nl];B[mm];W[ml];B[ee];W[gf];B[eg];W[fh]
;B[dg];W[gk];B[hl];W[hb];B[gb];W[do];B[eo];W[co];B[fn];W[ch];B[dh];W[af];B[ae];W[ag]
;B[bd];W[di];B[fg];W[gg];B[ed];W[om];B[on];W[ol];B[nn];W[hd];B[og];W[oh];B[of];W[nb]
;B[nc];W[ld];B[md];W[ga];B[fa];W[gl];B[gm];W[ha];B[ff];W[ka];B[la];W[ja]C[This connect is sente.]
(;B[fe]C[You cannot tenuki. See var.];W[od]LB[oe:a][fe:b]C[This happened partly because you tenuki (b), but parly also because of the bad shape (a), go back and look at move 35.]
;B[ne];W[mb];B[mc];W[ob];B[oc];W[ma];B[ek];W[fj];B[fk];W[fl];B[el];W[gj];B[ck];W[bk]
;B[cl];W[ge];B[il];W[ij];B[eh];W[ei];B[dk];W[dj];B[ni];W[lj]
(;B[];TT[]W[]TB[aa][ab][ac][ad][ba][bb][bc][be][ca][cb][cc][ce][da][db][dc][dd]
[df][ea][eb][ef][em][en][fb][fo][gn][go][hm][hn][ho][io][jn][jo][km][kn][ko][ln]
[lo][mn][mo][no][oo][de][in]TW[lc][le][lg][lh][li][lk][mc][md][me][mg][mi][mj][na]
[nc][ci][ne][nf][nh][ni][nj][nk][oa][oc][oe][of][og][oi][oj][ok][ah][ai][aj][ak]
[al][am][an][ao][bh][bi][bj][bm][bn][bo][fi][gh][gi][he][hf][hg][hh][hi][ia][ib]
[id][if][ig][ih][ii][jc][nd][jd][je][jf][jg][jh][ji][kb][kf][kg][kh][ki][kj][la]
[lb])
(;B[nh];W[nd])
(;B[nd];W[nh];B[na];W[od])
(;B[nd];W[nh];B[];W[])
(;B[na];W[nd])
(;B[nh];W[nd]))
(;B[od]))
(;B[ne]C[Just connect.]))
(;B[ne]))
(;B[ld];W[ke];B[dd]))[/sgf-full]

Sorry it is even more complex

Click Here To Show Diagram Code

[go]$$W
$$ +-------------------------------+
$$ | . . . . . X O O . O O X 1 2 3 |
$$ | . . . . . . X O . O X X . O O |
$$ | . . . . X X X X O . O X X X X |
$$ | . X X , X O O O . . O O X . O |
$$ | X . . . X X O . O . O X X X X |
$$ | O X X . . X O . . . . O O X X |
$$ | O O O X X X O . . . . . 5 O X |
$$ | . . O X X O O , . . . , O 4 P |
$$ | . . . O O . . . . . . 7 6 X 0 |
$$ | . . O O O O O O O O . O . 8 . |
$$ | . O X X X X O X O X O . . 9 . |
$$ | . O X X X O O X X X X O O O O |
$$ | . . O X . X X . X X . X X X O |
$$ | . . O X . X . . . . . . . X X |
$$ | . . O O X . . . . . . . . . . |
$$ +-------------------------------+[/go]

By capturing Black gains an extra libery and therefore can atari with an

Click Here To Show Diagram Code

[go]$$Wm11
$$ +-------------------------------+
$$ | . . . . . X O O . O O X O 4 O |
$$ | . . . . . . X O . O X X 2 O O |
$$ | . . . . X X X X O . O X X X X |
$$ | . X X , X O O O . . O O X . O |
$$ | X . . . X X O . O . O X X X X |
$$ | O X X . . X O . . . . O O X X |
$$ | O O O X X X O . . . . . O O X |
$$ | . . O X X O O , . . . , O X P |
$$ | . . . O O . . . . . . O X X X |
$$ | . . O O O O O O O O . O 1 X . |
$$ | . O X X X X O X O X O . . O 3 |
$$ | . O X X X O O X X X X O O O O |
$$ | . . O X . X X . X X . X X X O |
$$ | . . O X . X . . . . . . . X X |
$$ | . . O O X . . . . . . . . . . |
$$ +-------------------------------+[/go]

_________________
Promotor and Librarian of Sensei's Library

This is not what happened in the game.

@EdLee: Oh, haha, I sorta skipped to the end of the thread and didn't see the sgf!

@willemien: Lol, I didn't notice that shape down there, of course you're right, it's not seki if black can get another liberty...

_________________
That which can be destroyed by the truth should be.
--
My (sadly neglected, but not forgotten) project: http://dailyjoseki.com

At move 98, 3 things should be setting off alarms in your brain.

1) You have no outside liberties.

2) The marked stones have horrible shape. White has the vital point which you really want for yourself.

Click Here To Show Diagram Code

[go]$$Bc
$$--------------
$$ . W W B . . . |
$$ . W B B . W . |
$$ O . W B . X . |
$$ . . W W X . . |
$$ . . O X X . X |
$$ . . . O O X X |
$$ . . . . . O X |
$$ . . . . O . O |
$$ . . . . . . . |[/go]

In other words, you should look at the corner and visually abstract this pattern out of the surrounding clutter:

Click Here To Show Diagram Code

[go]$$B
$$ . . . . . .
$$ . . X . . .
$$ . . X . O .
$$ . . X . . .
$$ . . . . . .[/go]

...and it should set off an alarm.

3) He has a sente play against the lower part of your group, and you have bad shape there too:

Click Here To Show Diagram Code

[go]$$Bc
$$--------------
$$ . O O X . . . |
$$ . O X X . O . |
$$ O . O X . X . |
$$ . . O O X . a |
$$ . . O X X b B |
$$ . . . O O B B |
$$ . . . . . O B |
$$ . . . . O . O |
$$ . . . . . . . |[/go]

The fact that he can play 'a', making a false eye of 'b', should set off a third alarm.

_________________
Help make L19 more organized. Make an index: https://lifein19x19.com/viewtopic.php?f=14&t=5207

Thanks for the advice and analysis...when I've studied another month or two I might understand more of it.

I've just thought of another way of thinking about this, which may (or, then again, may not) be of help. (As someone who only started to play almost exactly a year ago, I still welcome the chance to be made to think more deeply about things like this, even though it must be obvious to the experts ). An "eye", often defined loosely in terms of a point (or set of points) completely surrounded by one's own stones (and possibly the edge of the board too), should I think, to be precise, really be defined as follows:



From this definition, of course, it easily follows that a group with 2 (or more) eyes can never be captured, no matter how many consecutive plays your opponent gets. Also (of which the above is a corollary) that the final liberty in an eye must always be the last liberty filled (if you're trying to capture a 1-eyed group), hence all the advantages of having an eye in a capturing race.

But, according to this definition, what you had in the corner there was not an eye! This is because, while one might naturally think of it as a 6-space "eye" (perhaps "pseudo-eye" would be better - note that this is completely different from a false eye), you actually only have 4 liberties there (count them!). This means that your opponent can (given enough plays - as happened here) indeed fill them all without committing suicide along the way, despite the fact you had a genuine eye elsewhere in the group.

So this is why, if the opponent makes an eye inside your "eye", it isn't an eye, because it means that your opponent can fill your liberties without leaving himself with none (as he has the inside of his eye as an unfilled liberty).

This post is, I realise, somewhat in the style of our resident rules authority, which can't be good, so I'll stop here

Incidentally, I think this kind of thing is very easy to miss - at least at my level. I've had games where I've had a group in the corner that I'm sure is alive, and when my opponent played some stones inside still thought was seki, but I later realised (or had it pointed out to me at the end of the game), that my group is in fact dead - because I'd missed that my opponent had (or could easily make) an eye inside

a complete wrong idea about go rules.
In most rule sets you won't see any reference to eyes at all. rules only talk about capturing, capturable and things like that.

That a live groups have 2 eyes is only a strategic concept, nothing to do with rules. (but that doesn't mean that it is sometimes handy.

for a good definition on eyes see: Bensons Definition Of Unconditional Life.

and then notice that indeed the "eye" is indeed not a Benson "vital region". because there are empty points that are not liberties of any black chain.

But do remember groups don't need to be benson alive to be alive

_________________
Promotor and Librarian of Sensei's Library

No, I agree - I never said my post was anything about rules

You don't even need to be alive to be alive-- just more alive than at least one nearby enemy group...

_________________
That which can be destroyed by the truth should be.
--
My (sadly neglected, but not forgotten) project: http://dailyjoseki.com