# Tag Archives: LPO

## A Trials Experiment with Golden Nugget

This post and the next illustrate the ability of an LPO pattern trial and Sue de Coq verification trials to penetrate the candidate fog of an extreme puzzle, thus allowing advanced methods to solve it.  The subject in this case … Continue reading

## Shortz’ Ferocious Hall of Mirrors

This post recounts the solving of Beware 190, the review puzzle from Will Shortz’ collection book Ferocious Sudoku which has multiple solutions.  On another multiple solution puzzle, Frank Longo’s  Absolutely Nasty Level 4 puzzle 61(Review Snaps II 3/12/13), I used … Continue reading

## Unsolvable 40 Logically Solved

In this post we checkpoint the solution of Stuart’s Unsolvable 40, via LPO and a coloring cluster extended by pattern slinks.  The solution of this puzzle by pattern analysis expresses well the ideals of Systematic Sudoku, and demonstrates what can … Continue reading

## Scrounging for New Pattern Sets in LPO

Here we attempt a more satisfying victory over the Stuart Unsolvable #40, by using the pattern reductions of the first pattern sets to add new pattern sets, moving closer to the full Pattern Overlay Method.  This series of posts on … Continue reading

Posted in Extreme Solving | | 1 Comment

## Searching for Orphans in LPO

This post illustrates the search for orphans in my Limited Pattern Overlay method.  Orphans are what we going to call candidates not belonging to any completed pattern.  Orphans are found by means of the freeform diagrams, as illustrated in Pattern … Continue reading

## Unsolvable 40 is Solved?

In the last post, Unsolvable 40 was staggered by a remarkable combination of coloring and LPO.  Only one pattern, 8b, was removed by LPO conflicts.  But other conflicts combined to force another pattern 8c to the color blue in an … Continue reading

Posted in Extreme Solving | | 1 Comment

## LPO vs Unsolvable 40

This post applies Limited Pattern Overlay, the sysudokie’s POM, to an Andrew Stuart Unsolvable, #40. The interplay of coloring and LPO patterns ties this beast up for the kill. Here is the grid as we apply LPO: My freeform LPO … Continue reading

## Toxic ALS in Unsolvable 40

Our struggle with Unsolvable 40 continues with a detailed walk through of the search for ALS toxic sets, and an analysis of the its stuck number ALS. Here is our grid with row ALS superimposed on a thin, as yet … Continue reading

Posted in Advanced Solving | | 1 Comment

## Advancing to LPO on Unsolvable 40

This post confirms the intractability of Andrew Stuart “Unsolvable #40” to SSOB  bv scan, X-panel analysis, coloring.  In preparation for Limited Pattern Overlay, a shortcut AIC reduces the number of patterns  for the number 8, and a coloring cluster is … Continue reading