A Tough Nugget Removal


This post illustrates how advanced techniques are employed in a series  of Sue de Coq verification trials on a super extreme puzzle.  The series was begun on the Golden Nugget in the previous post,  with a partial pattern of five candidates common to less than an eighth of the 2-patterns. It was enough to penetrate the fog of candidates effectively, but was not expected to hit on the solution.

Nug sdc 4vI left for my diligent readers the verification of the Sue de Coq NWr3 = 3(4+6)(1+7).  The alternative (4+6) cannot be missing, as this forces two 5’s in c3, as graphically demonstrated at stage right.

Yes, I discovered this in the trial trace. By the way, give yourself a treat for knowing how the orange and red colored ALS  created the Sue de Coq.

So the verified Sue de Coq requires 1 or 7 in r3c8,

Nug 197 nt orangeand we get  two new clues and a naked triple 178 in c8.

The marking continues until we reach the  near BUG below.

Nug 1787 trialNug near BUG

With visions of a solution, we follow standard advice and fill the 3-candidate cell r8c9 with 8. That has the added effect of choosing the cluster color blue.

The result is a near miss with all boxes satisfied except SouthWest.

Nug no bugYou may have noted  that removing the 7 in r8c9 leaves a complete blue green BUG, and wouldn’t be great if that signaled two solutions?  Well, curb your enthusiasm.  The uncolored candidates remaining form a contradiction, forcing two 7’s in r3 or r7.

Finally we have rejected Cr4=197, and thereby verified the Sue de Coq Cr4=9(3+5)(1+7).

Nug sdc reward

The Sue de Coq immediately rewards our patience with three clues,  a naked triple closing c7, and a 4-wing.

The marking below reveals, along with a neat 1-chain ANL, the long awaited contradiction to remove one 2-candidate!

Nug 2 remove traceNug 2 removalThanks for wading through all of this.  Though we missed the solution, we saw how a super extreme can be whittled down, and eventually solved by LPO analysis and advanced methods.

We also learned that, while it may be possible to use a partial pattern to burn off enough candidate fog for advanced method trials, we should check first that the removals we are after are decisive.

Our encounter with Golden Nugget  suggests that more is needed to penetrate the fog of candidates.  Next time, I begin a study of a computer solving approach that has been used on super extremes.

I’d like a human engineered version, to at least enable advanced level trials similar this series .  The project is similar to my adaptations of POM, the Pattern Overlay Method, into the several forms of LPO, the Limited Pattern Overlay, that were so successful in the extreme level KrazyDad Insane collection.

Also,  I expect to report soon on the second annual Akron Sudoku Tournament, put on by the Akron-Summit County Library in Akron, Ohio,  my home town.  Maybe you’re close enough to come.  It’s in the Meeting Room 2AB of the down town library 1-4 pm EST, Saturday,  November 9.  Email Deb at popdiv@akronlibrary.org to register.   I’ll be there and you know what I look like, so come by and admit to being a reader.  I  know you’re out there, but I’ll be awestruck  to actually meet one.

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About Sudent

My real name is John Welch. I'm a happily married, retired professor (computer engineering), timeshare traveling, marathon running father of 3 wonderful daughters and granddad to 7 fabulous grandchildren. The blog is about Sudoku solving. It covers how to start, basic solving to find candidates efficiently, and advanced solving methods in an efficient order of battle. It is about human solving methods, not computer solving.
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