Can anyone help me out on this 9x9 game?
I play White and by move 55 I thought the game was over and I had won. I have sente and I waste it filling a neutral point. Then Black’s next move kills my group in the lower left and the game is lost.
I did not see that move coming at all and I wonder how should/could have recognized the danger.
Suggestions?
60 at B4 keeps your stones connected and safe.
Thanks you for the review. I hadn’t see that move either…
I wonder if you have a suggestion on my original question: at move 55, what’s the pattern in the lower left that should have alerted me to the danger of an invasion? The lack of connection at B4?
I guess getting familiar with cuts and peeps might help. Although maybe it just comes down to experience
https://senseis.xmp.net/?Cut
https://senseis.xmp.net/?Nozoki
Indeed whenever your groups are not solidly connected you should consider whether disconnecting them is possible (because it usually leads to trouble - unless both groups can make life locally for themselves).
in the linked game B3 is “peeping” at your connection, threatening to push in and occupy the only point that would connect your two groups… But once you played enough games, I think you will just “see” it naturally, so I would not worry too much if it seems complicated for now.
Also just for funsies I left you a variation where I think white can still win the game even after the blunder 
Many thanks to all for the insightful comments and to @AdamR especially for the meme, which hit the nail straight on the head. In fact, i realize now that my biggest mistake—even bigger than the last 3 or 4 stones I played—was to resign. The game was not lost, I should have tried harder. And I should get better at counting…