UHC 177 Stretches It Out


In this post, Heine’s left page ultrahardcore 177 gets from one cluster wrap to two more in a long series of AIC and boxlines.

Continuing from the green wrap of last week, blue SW3 takes the last r9 5 outside of the South box, for an Sr9 boxline in the 5’s.

There’s enough bv to start a another cluster, but we continue in AIC building. This looks like a 1-way starting from 2r6c5 that happens on an ANL. Or you can put in that last wink into 2r6c6 and call it a simple 1-way.

Now after C2 => NE2

creates a tight little sequence of three events. First a 6-5-6 AIC ANL removes 6r3c12 for a pointer group 6r2c13 removing  6r2c6. This removal invokes a pointer group 6r13c5, or if you prefer,  boxline Sc6, removing 6r79c5.

Finally, an XY ANL.

A simple chain gets 5r2c6, and an extension gets 5r2c4, together invoking the boxline NWr2 removing 5r3c1.

Beebys’s next AIC ANL brings a follow up

allowing two more simple chains that wrap red.

The first is an XY ANL expanding the cluster.

The second is an XY ANL trapping red 4r4c5 and 4r7c4.

In what’s left, we have a pink and tan cluster. It traps 2r2c2 and wraps pink when two pink 8’s are forced in c4.

It’s a blue, orange and tan solution,

Next is left page ultrahardcore 221.

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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