Hi, I’m using a smartphone app to practice some tsumegos. But I’m having trouble with the solution of this one. I guess I found a way to make it seki. Did I missed something obvious in my solution or is the tsumego really wrong?
I’ve created the situation in this demo board: https://online-go.com/review/187785
Well, seki or not, it’s Black playing A18 to live (that is, to avoid being killed). The only problem I see is that your app shows suboptimal play for White. Which happens with tsumego software all the time. 
And for white seki is better than getting killed. The objective is to find the optimum sequence for both sides.
Still, black makes more points in the variations suggested by the app.
@wegenerd great find! I wouldn’t put too much blame on the app as this seki is not easy to read.
Okay, thanks for your answers! I was just surprised about my finding, since I thought a couple times that there were mistakes, but after thinking long enough I always realized that I just have overlooked something. So I just wanted to make sure that I’m right, since I didn’t expect to find “erroneous” tsumegos (suboptimal playing of white) with my skill level