kovarex:
@posetcay: Can you please show which variation you added? It still seems to look like just KO+ (instead of the original KO+2)

kovarex:
Also, note that when white answers correctly, the variant leads to the previous problem in this collection.

kovarex:
Less then half a year later, I could transfer this problem to be status based to make it much clearer what is going on. While I was checking this problem out, I discovered several issues: 1) The proper result of this seems to be KO+, and not KO+2, as whites answer in some of the variants was wrong. In this position, white did answer to E2, which leads to the KO+2 indeed, but just taking the stone as in the updated tree, it leads to just the KO+ 2) Some alternative orders of moves or refutations were missing: P.S. If anyone wants to check these chagnes, I will welcome it.

kovarex:
Yes, but extra local threat has the same value of taking or not taking first. So I think it would be fair to only accept variants with the extra local ko threat.

kovarex:
There is an interesting inconsistency in this problem. KO- is ko where opponent takes first, KO+ is is when I take first, and KO+2 is when Opponent has to add one extra threat and I take first after that anyway. KO- variation is marked wrong, as there is better KO+ variant. But there is also KO+2 variant which is the "same correct" as just the KO+. Shouldn't only the KO+2 be marked correct? The KO+2 is for example: S3, T3, T2, T1, N2, O2, Q2, P2, S1, R1, Q1, N1. Now black takes the ko, and is leftwith the extra local threat at P1. But Playing P1 before Q1 leads to a correct solution, where P1 was already played, and it is basically 1 local ko threat less.

semelis:
After the B17-A17 exchange, A18 can be played before G18 also.