Puzzle Description:

Foo Fighters logo from their 9th album, Concrete and Gold

#1: David Bouldin (dbouldin) on Mar 22, 2018

Have to say that love the fact that this solves out with line logic except for one move. There are probably multiple moves that will break it free, but I love the one I found. Curious to hear what move other solvers find before I share mine :)

Also, this was SUCH an amazing concert! The opening act played for almost an hour and then the Foo Fighters played for three more!! They played a bunch of new stuff, all of their past hits AND a couple of covers! Highly recommend if they tour near you!!

I took a look at the clues that were left, realized that all the 5s were going to be fat diagonals, and clicked the natural starting point of one of the diagonals. (R2 C12)

you always have such a way with logic that isn't pure logic, Kristen...extremely good at "intuitive logic" for puzzle-solving :)

i'll say there is a more "nit-picky, detail-oriented, step-by-step" logic move that gets you there too ;)

Trying to place the nine on C16 was my break!

I didn't make a note of my guess, but it I think it was C11 R3 or near there. I thought with three fives that my choice would be somewhere in the top of the first 5. And it worked. Everything fell into place from there.

i'd love to hear the specifics of that jota! i tried to figure out a way using that 9 but couldn't find one.

my move is most likely "deep lookahead" but it most definitely NOT guessing :)

- C3R20 and C8R20 can't both be black or it violates R15

If the 9 starts at row 2, it will not work, deep look ahead, same with row 3. Definitely not guessing!

Found to be solvable with moderate lookahead by infrapinklizzard.

Both David's and Jota's methods work.

Another way to look at David's:
After line logic,
The 5s in row 20 could be either both in the left section, or one in the left and one in the right.
If they are both in the left then:
> r20c2-5 & r20c8-11 would be black.
> which would trigger the 5s in c3 and c8,
> both of which would make r15 white in their column.
>> which would leave no space for the left 5 in that row.
= since our original assumption must be wrong, one of the 5s in r20 must be in the right section and so r20c16-18 must be black.
Then LL to finish
This is deep lookahead.

Jota's is a two-clue edge logic.
After LL,
If the 5 in c16 crosses r21
> it would trigger the 4
> which would then trigger the 5 in c17.
= This limits the lowest the 9 in c16 could go to r15.
(Which then with line logic makes c16r7-9 black.)
Then LL to finish.
I would call this (barely) moderate lookahead*, but (definitely) hard to find.

*This is a kind of extended edge logic. Being one step past a normal advanced logic puts it on the borderland between moderate and deep. It usually gets put in moderate.

Looking back, I guess I did Jota's differently than she did. I must admit I don't see her method. You can go a long way without error with the 9 in r2...

Another note - Since the puzzle is rotationally symmetrical, David's hint also works starting with the 5s in r6, and Jota's (well, mine that was inspired by Jota's) with the 9 in c10.

sounds like you had a lot of fun working on this one joe ;)

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