This post backs up your lite coloring effort, I hope, on KrazyDad 425. The initial lite trees deliver a cluster merge, and as these grow, lite coloring gives two confirmations and a coloring wrap to finish without trial.
The first objective was the cluster merge. Coloring gives you a color bridge, when green and red in the Northwest box declares that green and red cannot both be true, so either blue or orange is true, if not both. Now any candidate seeing both is false.
But lite coloring does more. Red 3r2c3 winks at green 3r3c2, which slinks with any blue, by definition. So if red is true, blue is true – a coloring cluster merge.
The merge follow up
allows a 1-chain ANL, expanding the cluster.
Let’s walk through the added lite trees. From now blue 1r4c9, wink to 1r1c9 and slink to 7r1c9 for the first arrow, then wink to 7r2c7 and slink to 1r2c7, then wink to 1r8c7 and slink to 6r8c7. Combine that with the tree from green 3r2c5 to 6r4c4, and we trap 6 r4c7.
Continue from 6r8c7 with wink to 6r8c5 and slink to 6r7c5. Add the arrow from green 7r3c5. 6r7c5 is green lite and blue lite. It’s a lite coloring confirmation!
Following up with S6 => SE47, there’s an expansion trap on 1r4c1, and a tidy ALS_61 with a Cc5 boxline taking advantage
We add a green lite tree, then realize we can extend the blue lite tree to 6r1c6, doubling up with the green lite tree already there. Now 6r1c6 is true regardless of which tree becomes true. One does.
Now it gets a little hard to follow after
N6 =>(C6, N2, N4)
when ALS_54 overwrites the arrows. How do you spot such a thing. The X is easy enough, but the ALS skipping 4 and the 4 value group? No way.
The last 4 in c3 becomes SW4, and a naked triple 279 comes out.
And finally, after
a lite coloring wrap. If green is true, two green S7’s, and blue mops up.
To end lite coloring look backs, we go back to an Dov Mittelman email early in the ultrahardcore review, which he later had to explain to me, about his “light coloring”. Yes, I changed it to ‘lite’ after, rather than ‘light’ before. I also put in arrows, specifically representing wink to slink lite tree segments.
Go back to A Coloring Trial Weakens UHC 311 of November 17, just before the coloring trial. You just might be able to step in with lite coloring, and avoid the trial, by getting a wrap. And if you’ve been hanging back, you just might be availing yourself of this crazy blog.
Systematic Sudoku 