Pattern Trials of Insane 475

After a week’s technical delay,  let’s conduct our third trial on KrazyDad’s Insane v.4 b.7 n.5. The first two trials validated Sue de Coq chutes, removing candidates.  This is often necessary with tough puzzles, to verify that alternative values are not absent in the chute. The trial of this post is assembled by a long AIC chain, and enables us to remove, not just candidates, but patterns.  In this post, two successive trials of pink olive analysis patterns continue trimming patterns, reaching a solution.

From our position in the previous post, the AIC trial trace is

IN 475 AIC traceIN 475 AIC trial gridA graphic representation of the solving path shows that seeing the earliest contradiction without the aid of the AIC would be very unlikely.


The failure of the AIC chain gives us merely a 3-clue in  r1c9. But this clue suggests we do a second pink olive analysis on the 3-patterns.


IN 475 3 pink olive 2This time there are two pink patterns that share three of the seven candidates.   A trial of these three candidates could either include the true 3-pattern and prove a solution, or would at least reject the pink patterns.

The trial trace is very short,

IN 475 3 trial


IN 475 3 trial gridshowing that either of the pink patterns will strip both 6 candidates from the North box.  The graphical version derived from the trace shows this directly.

The remaining four olive 3-patterns orphan three 3-candidates.

At this point I did a review of the current state, looking at updated bv maps, x-panels and pattern panels.


IN 475 2 pink oliveSome daylight appeared in the 2-patterns, prompting  a pattern slice that revealed two pink patterns sharing four of 7 freeform candidates. Olive patterns were enumerated only far enough to determine there were no orphans. On yet another trial, this time of the four common pink 2-candidates, Insane 475 finally gives up.

The trial trace and color coded solution follow.


IN 475 2 po traceIN 475 solutionKeeping  score on the guessing war, we now have a second Insane that has forced us to use trials.  But in doing so, the collection has helped me demonstrate a variety of trial formulations that make steady progress toward a solution, avoiding a tiresome sequence of unproductive guesses requiring complicated backtracking.  Every trial required the advanced assembly of a set of trial candidates.  There was no “stab in the dark” guessing.

We move on to Insane 485, which I hope you have already found to be much easier.  In my case, box marking was unremarkable, but the puzzle barely survived line marking.

After the wild line marking of the following 2-D trace and tamed grid below, I could complete the solving with bv map and coloring. Maybe you’d like to try it, and find the surprise at the end, before it is revealed in the next post.

IN 485 basic traceIN 485 LMAlso, get ready with your basic sysudoku solving of Insane v.4 b.9 n.5 .


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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