See Critical Notchers on sensei's for the basic idea.

I'm wondering if a heuristic can be formed which can tell me how strong or weak a notched group is, and whether it should be killable. So you'd assign points for stones on the second and third line, and subtract points for weaknesses, and if the score is larger than some number the group is alive, and if it's below some number the group is dead. Similar to capture races.

So for the trivial case of stones on the second line without weaknesses, there's that familiar "six live eight die" rule. Connecting to the corner on the second line adds 2 extra points, since 5 stones on the second line attached to the corner are determined by sente. Stones on the third line need to be 5 long and have sente (I think that's the rule) to form life. So you'd probably find the common denominator and give stones on the third line 7 points and stones on the second line 5 points, and the group lives if it has more than 35 points. And on like that.

Is such a heuristic possible? Or might it be unreasonably complex?

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1k KGS

not answering the question but isn't it just easier to read it out?

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I am John. John-I-Am.

Sometimes. Like with capture races, there are a nice set of heuristics from this book that you can use to see who's going to win the capture races. Sometimes it's easier to just read out (usually when it's small and simple), other times the heuristics are invaluable (large eye vs small eye + lots of internal liberties + kos).

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1k KGS

Just knowing the result is much more effective, because you would be able to read deeper. It's the same with nakade shapes: When you know whether such a shape is dead, you don't have to read it out. Knowledge is what enables effective reading.

But reading it out until the shape is hardwired in your brain will improve your reading on the way.
Just relying on a heuristic to know "this is alive" won't help you if the other player tries to kill it. In that case you still have to read it out.
If you on other hand, have hardwired the shape in your brain via extensive reading, you can answer the attempts correctly without thinking. Just like nakade-shapes

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Magics way up the hill (personal study journal)

So I'm going to try and tackle this since I can't find anything on it. The goal is to get an equation where you plug numbers in and get back the relative strength of the group numerically, and then turn that number in to a status (alive, alive with seki, alive with ko, life and death (eg: determined by sente), dead). Not sure how useful it will be but it's sort of a fun math-y exercise.

I might post some status questions once I dig in to this a bit.

Also, if players strong(er) in life and death would share any of the rules they use when judging a position, I'd find that useful. eg: "six die, eight live". Though maybe all stronger players just memorize all the positions and read it out when in doubt. I guess I don't really know.

edit: ah actually I have a fun problem already. Given the "notch code" that the sensei's library page uses, is there ever a time when a group: XYZSW is alive, but XYZWS is dead, or vice versa? Or likewise with N?

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1k KGS

If I understand your question, the answer is yes: check out 116NWNotcher and 116WNNotcher. I was the one who started overhauling the format at TableOfNotchers, but I never got around to finishing it. It's a little time consuming and I have a hard time getting the diagrams to format the way I would like. If someone else wants to take a stab at that page, I would appreciate it

Yeah I came across that example today.

Is the status for both those groups correct? The 116NW page lists the reason it's alive is that it's eight long, but I think that reasoning is off (even if the status is correct), since there are certainly groups on the second line that are eight long that are unsettled (eg: 116WW).



I'm probably going to start stabbing away at it this weekend. I might also expand it to treat cases where there are stones on the first line, since I have a few examples where a dead shape can be put into limbo by adding a stone on the 1st line (either a hane or descent). But one thing at a time I guess.

A lot of the statuses are unfinished or maybe questionable (no sources, just an entry in a table). Maybe people could list any sources (publications or whatever) they know about the status of different notchers (and list the notcher and the status the book gives) and I can integrate them into the page so it has a bit of authority behind it? Or if there's a life and death database somewhere I can consult?

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1k KGS

I think the 116NW is referring to "six die, eight live" for groups on the second line.

If you took the time your going to spend to create the formula and did tsumegos instead im sure you would be able to know the status of all different kinds of notchers

Right, but that doesn't necessarily apply to notchers, because the weakness created by a notch might make it killable. See this example (which ironically quotes the rule again). The eight need to be all on the second line without defect for the rule to really apply. Anything else is governed by a different rule.

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1k KGS