Practical Endgame Test 2 / Book Solution - Black

1 - The big ideas  

White's marked stones are suffering from too many cutting points plus a shortage of liberties. As a result Black can jump in to 1, making the upper left corner the largest play on the board. After White ends in gote with 6, Black plays 7 which is another nice tesuji in this shape with the cutting point at a. Black threatens the follow-up shown below. Before answering 7, White turns to the bottom side where 8 and 10 threaten the life of the bottom black group and are absolute sente.

1a - Follow-up  

Black plays 1 and White cannot intercept at 3, or else Black will cut at a and descend to 4 capturing all the white stones. After White answers at 2 he also has to connect at 4 (or a), ending in gote. Note that if Black plays hane at 3 directly without playing the marked stone (7 in diagram 1) first, White will reply at 1 and not have to connect. Thus Black will give up sente for only one additional point compared to the solution diagram.

2 - Cleaning up, 9 at 6  

After forcing Black along the bottom White returns to the upper right corner. Black 3 and White 4 follow and the last interesting point comes after Black 5. White has to answer since Black threatens to cut at a creating a shortage of liberties for White; and then capture two white stones with a play at 8.

White throws in at 6 before playing 8 himself. This does not earn any points but is good technique worth remembering. The exchange of 6 for 7 makes the point b a source of two ko threats should a ko fight develop later in the game. White 10 ends the scoring. In filling in the liberties White will have to add a stone at a while Black will have to connect at c. The final result is a tie (jigo).