TherapieGo: I see where you're coming from, especially if we're analyzing from a points-efficiency perspective with perfect ko management. But in practical terms, especially for mid-level players or in tense global situations, choosing a gote seki provides guaranteed life and avoids the risks of ko fights that could backfire hard.
Yes, B19 leading to mannen ko can be sente and theoretically worth more. But that’s assuming the player can maintain the initiative, wins the ko threats, and the rest of the board allows it. In real games, the value of stability and zero risk often outweighs theoretical point gains from risky ko dynamics.
So I’d say: ko might be locally better, but seki is often globally wiser. ------------------ CHAT GPT xD
caranthir: I edited my earlier message several times, so you might have been looking at a version that I already wrote over. To recap, my "mannen ko in sente" is better (about 10 points better, so it's actual suicide for the opponent) only if the opponent takes gote to accept the mannen ko. If they play away instead, it's about equal to the seki variations. I accepted the seki variations. The only stuff not accepted are the unfavourable direct kos. -------- I think mid-level players should appreciate the fact that a mannen ko for instance is practically seki almost always. One doesn't usually have to take any out-of-the-ordinary heed of ko threats just because there's a mannen ko on board. This collection (L&D advanced) is on average not even mid-level but (in my opinion) pretty high level.
posetcay: Living in seki is better than living with ko %99.9 of the time. If I am playing a local move, B19-B18-C19 is the obvious sequence here to me. Otherwise I would just tenuki. I don't agree with forcing a ko sequence with a hint.
caranthir: On an empty board, tenuki is indeed a possibility. But if you're going to play anything at all here locally, the logical way to me (without even thinking) would be to play something that ends in sente and at the same time makes the group practically alive. ------ Looking at Katago evaluations closer, your suggestion of S1S2R1 isn't so bad - its value is equal to S1S2T2. It's only if the opponent (after S1S2T2) then plays R1 to create mannen ko in gote where they trick themselves into making a 10 points mistake. So if S1S2T2 was any better, it would be because it has the practical possibility to be a lot better (though admittedly the practical tricksy aspect might be outside the proper discourse here). So, the fault in my thinking - about ending in sente - was that I end in sente here only if the opponent co-operates.
caranthir: Should we accept sente (favorable or mannen) ko and gote seki variations here alike? Arguably it could make the thing very ambivalent where virtually anything goes and potentially teach bad habits too. On the other hand, also arguably, it's often the student's responsibility to think about the applicability of the different possibilities that are present in a tsumego. Opinions?
TherapieGo: 101 Weiqi doesn't agree with that, but I guess everyone can decide what they want on this tsumego. ------ Here's the Tsumego link to 101 Weiqi and their decision in the correction. https://www.101weiqi.com/q/494/
caranthir: Yeah, the policy isn't trivial as to what should be accepted and what should not be accepted in a particular tsumego. Now here I kept the position open in Katago to make sure I don't hallucinate or anything. In Katago evaluation, all variations where we have gote seki are just trash, and it would be the same in a a real game except in special cases where we are leading more than enough but maybe are heavily disadvantaged in ko threats. (Q1 for instance is -10 points, not very far from literally passing, so I'll just say that if Weiqi 101 doesn't agree with this, then we shouldn't agree with 101 Weiqi.) -------- In order for the tsumego to be meaningful, the assignment should be framed (as in here, "favorable ko in sente" was the most accurate I could come up with). So with precisely the same starting position, there should ideally be two different problems, one where we should make ko in a beneficial way and another where we should make gote seki "just to make sure nothing's gonna happen ever".
caranthir: T18 has the same problem as Q19. Opponent can force a sente seki. T18 and S18 are the only decent starting moves. Both can lead to mannen ko but it's gote for the opponent to make it so. ------- If S18S19, the variation should end there (to force Q19R19 or Q19R19 isn't meaningful in any way.) I updated variations with the hint "1000 years ko in sente". It's enormously better than having seki in gote.
I edited my earlier message several times, so you might have been looking at a version that I already wrote over. To recap, my "mannen ko in sente" is better (about 10 points better, so it's actual suicide for the opponent) only if the opponent takes gote to accept the mannen ko. If they play away instead, it's about equal to the seki variations. I accepted the seki variations. The only stuff not accepted are the unfavourable direct kos. -------- I think mid-level players should appreciate the fact that a mannen ko for instance is practically seki almost always. One doesn't usually have to take any out-of-the-ordinary heed of ko threats just because there's a mannen ko on board. This collection (L&D advanced) is on average not even mid-level but (in my opinion) pretty high level.