Nakex 183 Hides the Keys


The last review puzzle, Nakamoto Extreme 183, follows the collection’s pattern of hiding easier removals behind methods that are very difficult to spot. An effective defense is to maintain bv maps, X-panels, and coloring clusters carefully as more advanced results are obtained.

The basic trace becomes a movie of systematic basic solving as you read it out on your own grid. Compare it to your own basic drill, both process and results.

A spotting note: the required slinks for the hidden unique rectangle Type 1  come from a frequently occurring dead X-wing.

 

 

 

Hidden pairs are more rare.

 

From the UR, with three 5’s removed, Sudokuwiki moves directly to the 5-panel for a grouped ANL.

 

 

 

 

 

 

 

After

 

 

 

there is a 4-BARN that might be spotted in the wake of the dead 2145-wing .  The wing’s 5 value set is toxic, but no 5 sees the whole set. The alternative 15 wing does no better.

Next ,  Nakex 183 enters AIC building with a bv boomer from 3r3c5, making a confirming ANL

N3 enables the APE below. The ALS outlined in red exclude 8 of the 15 combinations in cells r12c9.

 

 

 

 

 

 

 

It’s the common values with  the two ALS that make r12c9 a good candidate for an APE.  List the surviving (r1c9, r2c9) combinations: 13+16+21+23+26+53+61+62+68+83 and note that no x5 or x8 is listed. Listing in opposite order, we scan  16+31+35+38+61+62+68 with no 5x or 8x listed. Maybe you  would notice that 3 missing from the two ALS would make the second list shorter.

The next Sudokuwiki move is a second APE, made possible by this one.  Can you spot it? Next post will have that, the finish of Nakex 183, and the review table for Nakamoto Extreme.

 

 

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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