More 8-Pattern Trials on Unsolvable 190


This post continues  the resolution of the 8-patterns of Unsolvable 190 to a conclusion.  In the previous post, setup for the  double exocet solution was defined by a chute lettering table.  A freeform enumeration on the 8-panel divided six patterns into a blue set of two and a green set of four.  A trial of three common candidates  rejected the  blue set, leaving two sets of two patterns each, with common candidates now colored red and orange.  Sysudokie homework was to carry out the orange trial, with a trial trace.

Unsv 190 red orange gridHere is the grid as left by the blue 8-pattern trial. The orange trial is appears to clear more fog and allow advanced methods to be decisive, and the result will definitely define the 8 pattern  down to two, and may produce a solution.  So orange it is.

If you see removals  and confirmations  on this grid, let me know, and I’ll include them to your credit in a revised post.

After removing the red 8’s and those seeing the orange clues, the marking flowed on according conventions of the trace page.

Unsv 190 orange trial tr

But there it stopped, with what looked like a gated community of 1, 2 and 5 candidates, locked away from the rest of the puzzle.  By the way, a solution of the exocet happened while I was marking away.  Don’t hold your breath,  it has only 1 in 6 chance of being the puzzle solution.

Unsv 190 125 wrapSo what did you do when you reached this point?  I drew up a bv map, spotted the regular 125 wing, and scratched around to find  a 5 candidate that could see the second wing by ER, or as shown here by forcing chain.

Coloring wraps the aqua candidates, and  what’s left is an inconsistent placement of 1,2 and 5. The orange patterns fail.

 

Unsv 190 red 8 ANLThe winning red freeforms erase 7r9c7 for a new slink, enabling a 7-chain  almost nice loop to remove 7r3c9.  It doesn’t  seem to matter here, but it does have a decisive role later.

Of the two remaining red patterns,  I go for the solid line freeform, the one confirming 4r5c5.

 

 

Unsv 190 red trialIt goes directly to a weird contradiction, forcing the naked pair 79 and a 7 in the same box.

The final trial is done with the now known 8-pattern, and tests only the setup placements of 2 and 5 that allowed an exocet solution.  The trace marches down and across the page in a remarkable series of naked pairs, without pauses for wings, fish or chains.  It leaves a 190 solution with the exocet portion almost, but not quite, matching the one in the orange trial. I leave you the pleasure.

The dogged pursuit of the 8 patterns is only one of the pattern grinding alternatives to the conventional exocet trials.  Unsolvable 190 is a fine example for a thorough autopsy, with surprises.  Stay tuned for that, in the next three weeks.

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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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