Ultrahardcore Review ALS-wings IV

The survey of ALS-wings in the ultrahardcore review continues, with new wing building situations, another ALS version of the Death Blossom, and an amazing ALS.

In this UHC 267 ALS-wing it’s a two box ALS , connected by a column ALS. A natural spotting scenario on three ALS maps would be column first, looking for wink out connections on each end. But if we’re drawing the column ALS first, it’s not until we are drawing the East box ALS and looking box to box. In fact, it’s when we draw the East box and scan for lines to match it that we see it connect to the red ALS, and the match list reveals that c9 red connects to the NE blue.  On the victim hunt, we only have the chain ends to worry about, because red and blue ALS_3Z victims would be removed.  That leaves a green 1,7,8 vs. blue 2,8 to match up for the grouped ANL on 8.

In two Death Blossoms with stem r2c6, each 9 victim sees 9 value groups in two ALS petals. The value groups slink to singles seeing both candidates in the stem. If either victim is true the stem is stripped of candidates. Replace the stem with a bv with internal slink and it becomes a bv ALS-wing ANL.

Add a cell and value to one ALS and get another the ALS-wing, or Death Blossom, removing 3r6c4.

What happens here in our ALS-wing building process? It’s column vs box with the red ALS added before the blue one. Actually, if you are AIC building from each wink exit as the  red ALS is added, you’re at the 9’s in the Center box and at 5r2c6, so you could make the ALS connection with both blue ALS before they are drawn from the suset table.

That brings us to 311, and the ALS-wing that gave me pause about row vs column ALS matching.

Adding the red ALS after some AIC building, we might be scanning previous rows for matches for 6 in c6 as well as 1 in c5. As we add the column ALS, if we scan for matching bv for each single and aligned value group, we would not require the saved little green square in the red ALS row that we thought earlier  that we needed.

Instead, the blue scan for bv would trigger a row scan for 1 in c6, the match on the red single would call for a match of value groups, yielding the intersecting 8 groups and 8 victim..

This takes advantage of bv being marked on all three ALS maps.

Going on to UHC 355, here is a box ALS being scanned vs. the column ALS. With the new single marked on the column ALS, and the aligned value groups marked in the box ALS. The ALS chain defining the ANL is not hard to see.

UHC 399 brings another bv ALS-wing where the box ALS with attached bv is scanned over the row ALS. The scan matches the 6 from the preliminary scan of the red ALS for bv. This example exposes the fact that a line match should include a group within the box of a bv partner, here the blue single 6 in the SE box.  In addition to that 6, the red ALS is prepared to match row ALS values 1, 3, 4, and 7. I had to verify the blue ALS by writing out the suset r7  123579/1345678 !

Next week we finish the ALS-wing examples with five from UHC 443. Each post has brought some new insight on the DIY construction of ALS-wings. The next one is post 496.

I’m thinking of pausing the weekly posts, letting the 500th become the home page with navigation information and current news. The pause will allow long delayed blog improvements and the Guide to be completed. Perhaps later, a few puzzles of different levels of difficulty can be taken through the entire Sysudoku Order of Battle, as envisioned in recent posts.

About Sudent

I'm John Welch, a retired engineering professor, father of 3 wonderful daughters and granddad to 7 fabulous grandchildren. Sudoku analysis and illustration is a great hobby and a healthy mental challenge.
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