You played well in the opening and most of the middle game, well above 17K level I think. Rather than concentrate on the big mistakes (missing atari), let me mention a few places where you played too softly or complacently, where a killer attitude and a little extra reading could get you a much better result.
The sequence
to
put no pressure on B and let him take the entire corner. If we imagine a slightly different sequence of moves which gives the same result, that might make the loss clearer. Suppose
simply connected at P5, forcing B to respond at R5. After that, would W exchange P4 for Q3? That would be a terrible exchange, helping B make territory. But that is what happened in the game, by a slightly different order of moves. Can you think of something better here for W?
In response to
, B should probably play safely at R4. When B instead plays atari at R5, think about giving up this one stone to play atari at Q3 yourself. Next you get to play R3 to take the corner, which is a huge swing in territory, compared to the game sequence where B took the corner. The loss of a few stones on the outside is trivial in comparison.
The next place you played too soft was after
, a great move which should really have demolished the B side position.
should double-hane at J3. Try reading out some continuations. B can atari once, but after W connects I think you will see that B is in serious trouble. Your actual move gave B the opportunity to connect safely underneath. When B instead played H4, you should jump at the chance to separate B with J3. Finally, after the hasty
at J5, take a minute to see if you can get in a forcing move instead of simply connecting. If you play J3 now, B is destroyed.
Lets look at the whole board after :b115:. The focus of the game now looks like the upper side. B has a sketchy position here, and if he can convert much of it to territory, he will win. On the other hand, W has immense thickness in the upper right, and no weak groups anywhere, so he is in a good position to invade and dispute this territory. Moves like O17 or N17 or R17 or K16 or M16 come to mind.
The game sequence :w116: through :w122: is much too small and timid. The later sequence :w126: through :b131: is similar. In both cases, you let B consolidate more territory than you got in return. What is worse, the B groups that made territory were thin and insecure to begin with, while the W group that made territory was immensely strong. You need to strive for a better result.
:w132: was the right idea, a reasonably deep invasion backed by strong groups outside. The result through :w138: was a spectacular success. Do this more often
