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#1: Brian Bellis (mootpoint) on May 8, 2019 [SPOILER]

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After placing the second 3 in C10, I couldn't place the bottom four or complete the right bottom of the wheel.

I got through this okay -- color/line logic got all but a rectangle in the bottom center R12-20 C9-17 (77%) and then I dotted C9 R20 and R19 by edge logic. Then you can attack C17 R19-20 similarly. LL works now to solve things since C9/17 R16 are both black.

But given it's marked as "needs guesswork" I figured if someone else could verify, great.

Found to have a unique solution by valerie.

Andrew: Hm. When I get to 77%, I can do edge logic on columns 9 and 22, but that only marks a dot at the bottom of each column (row 20). I'm not getting a second dot at the bottom of each of those columns that you did, but also I'm only looking at one column that is the same as you, since you were in column 17 and I'm in column 22, though I'm guessing that's a typo and we are both looking at columns 9 and 22.

After that, I finished solving the puzzle by using trial-and-error, but that counts as guessing. So I didn't mark the puzzle either.

Using edge logic twice in each of the columns 9 and 22 is sufficient for me. It gets me two black cells in row 15.

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Glad to hear!

Hm. I tried solving the puzzle again. Again I got to 77% and did edge logic in columns 9 and 22. And again I got only one dot in row 20 from that, not a dot in row 19 or a black cell in row 15.

Describing the edge logic in more detail, in column 9 if I place the 4 in rows 16 through 19, then I can place the black 1,2,2,3 in rows 16 through 19, respectively, without any contradiction -- so edge logic isn't doing anything there. So I am still trying to figure out how edge logic can put a dot in row 19.

On the other hand, if I put column 9's 4 in rows 16-19 and then continue solving forward, that puts column 11's 2 in rows 19-20. That tells me that row 20's 4 must include columns 11-13, which puts a contradiction in column 12, which has a 1 at the bottom but needs to have a 2. So *that* tells me that I couldn't have put column 9's 4 in rows 16-19, which tells me that column 9 row 19 is a dot. But that's several steps of lookahead, not edge logic. And I think Joe would say that even trying the 4 there is guessing.

From there, there's a bunch of line and color logic. Then repeat the same steps with the 4 in column 22. Then line and color logic to finish.

So... I am not sure if that is "moderate lookahead," "deep lookahead," "guessing," or "I missed something" ???

EL R20 marks C9 & C22 white, same result as doing the EL on those columns.
EL C10 and C21 marks R14 white in both columns.

R12: If the black in C10 goes to the right, it whites out R14-20 in C11. This would force the 4 in C9 to cross R15-16, which in turn causes a contradiction in C10. Therefore R12C9 must be black. The same logic can be mirrored in C20-22.

LL will finish from there. My lookahead is 3 steps, which I think is barely in tolerance for "moderate," so that's how I'll mark this one.

Found to be solvable with moderate lookahead by wombatilim.

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