Also, we must consider the hane at A15 as well. After E15 F16 B18 C17 B17 C16 C15 B16 B15 A15, we have to exchange A14 A16 first. If we play D19 first, D19 C19 B19 E19 A14, black will no longer answer at A16, but rather fight the ko with A17. After A14 A16 exchange, white can no longer answer D19 with C19, but has to play B19, giving black the extra liberty he needs to win the semeai against the center group.
hello, very interresting problem, however, i can't see how it could be used in real game, since that kind of position never happen, specially with h19 for black, seem totally unreallistic to me. Thank you, for sharing, it was a real pleasure as always.
The purpose of these exercises is not to be "realistic" but rather to train our calculating skills. This problem is more realistic than many other problems, such as those in Igo Hatsuyōron. Glad you are enjoying it!
I thought this was honestly a quite realistic shape. The theme of nose tesuji to prevent white from extending liberties happens often, not just in the corner of the board. The tombstone sequence is a common theme to reduce liberties and squeeze bad shapes, as is the fight in the center (and why it's sometimes better to kosumi to threaten the snapback rather than squeeze and compromise your own liberties). Then the key idea of having a hane on both sides extending your liberties by 1 is often a tactical idea in a semeai. I would never find the solution at the board, but studying this problem definitely helps a lot in understanding the proper sequence of moves, and shows us a key idea in fighting-- leaning on one weak group/ cutting stones to make the attack on another one more severe.
I struggled with this problem for an entire day. I was stuck on what to do after E15 F16 B18 C17 B17 C16 C15 B16 B15 A16. The best I saw was ko after D19 C19 B19 E19 A15 A17 F19 H18 D19 ko, black takes first. However, then I realized white doesn't have to play H18, but can instead start the ko like A18 D19 A19 B18 H18 B19, and it turns into a multi step ko for black. However, instead of D19 first, black actually has time to play B19. I originally discarded this move because both white groups have 4 liberties, and playing B19 doesn't fill a liberty, giving white first move to filling liberties, but I missed the key resource of B19 E19 C19, threatening to bridge under. Now white can't connect at B19 and loses the semeai by 1.
Also, we must consider the hane at A15 as well.
After E15 F16 B18 C17 B17 C16 C15 B16 B15 A15, we have to exchange A14 A16 first. If we play D19 first, D19 C19 B19 E19 A14, black will no longer answer at A16, but rather fight the ko with A17. After A14 A16 exchange, white can no longer answer D19 with C19, but has to play B19, giving black the extra liberty he needs to win the semeai against the center group.
hello, very interresting problem, however, i can't see how it could be used in real game, since that kind of position never happen, specially with h19 for black, seem totally unreallistic to me. Thank you, for sharing, it was a real pleasure as always.
The purpose of these exercises is not to be "realistic" but rather to train our calculating skills. This problem is more realistic than many other problems, such as those in Igo Hatsuyōron. Glad you are enjoying it!
I thought this was honestly a quite realistic shape. The theme of nose tesuji to prevent white from extending liberties happens often, not just in the corner of the board. The tombstone sequence is a common theme to reduce liberties and squeeze bad shapes, as is the fight in the center (and why it's sometimes better to kosumi to threaten the snapback rather than squeeze and compromise your own liberties). Then the key idea of having a hane on both sides extending your liberties by 1 is often a tactical idea in a semeai.
I would never find the solution at the board, but studying this problem definitely helps a lot in understanding the proper sequence of moves, and shows us a key idea in fighting-- leaning on one weak group/ cutting stones to make the attack on another one more severe.
I struggled with this problem for an entire day.
I was stuck on what to do after E15 F16 B18 C17 B17 C16 C15 B16 B15 A16. The best I saw was ko after D19 C19 B19 E19 A15 A17 F19 H18 D19 ko, black takes first. However, then I realized white doesn't have to play H18, but can instead start the ko like A18 D19 A19 B18 H18 B19, and it turns into a multi step ko for black.
However, instead of D19 first, black actually has time to play B19. I originally discarded this move because both white groups have 4 liberties, and playing B19 doesn't fill a liberty, giving white first move to filling liberties, but I missed the key resource of B19 E19 C19, threatening to bridge under. Now white can't connect at B19 and loses the semeai by 1.