Stephens Extremes Snapshots I


Here we have highlight snapshots from the review puzzles from Paul Stephens’ Extreme collection.  Recent posts have been about the Stephens approach to basic and advanced solving.  The Sysudoku solving of two of the review puzzles, Weeks 48 and Addicts 148, was included.  This post is a quick tour of the most interesting happenings in the other review puzzles.

Week 44 double swordfishWeek  44 gets the tour off to a promising start with a double swordfish – but the fish, shown here,  got away.

That happened because the simple UR of the diagram collapses Week 44 right after line marking, before the X-panels are prepared. The 8-clue it produces in r6c5 is fatal.

I looked for fish on the X-panel anyway because Paul hinted there would be “bigger fishy patterns”.  In the same note he suggests using the  Nishio pins to look for fish.  The equivalent on PowerPoint is simpler and more effective.

Week 52 two XY-ANLMoving along on our tour, next is the final puzzle of Weeks, #52.  Are you ready for this?  After a pair of intertwined XY-ANL remove two candidates on the same line, we get to see . . .

two kraken swordfish on the same grid.  Astounding!  Notice the forcing chains of the kraken analysis.

Another warning: maybe you should look no further, but instead, buy Mastering Sudoku Week by Week, work on #52,  and use this post as a checkpoint Week 52  is not over yet.  Very intense coloring logic follows.

Week 52 3 clustersAfter feeding the swordfish, I got out the paint brushes and started coloring, splashing on a blue/green and a red/orange cluster as  is customary.  This left many connected by uncolored bv towards the southwest, so I slapped on an aqua/tan cluster as well. 

 

No traps but the bridging logic gives three toxic color pairs:

not(orange and green) => red 0r blue    

not(tan and green) =>  aqua or blue

 not(tan and orange) =>   aqua or red => one color trap.

Week 52 AIC nice loopWatch closely. Here is where the sysudoku  difficulty level moves up!  Adding AIC hinges, a nice loop with a blue green shortcut removes two decisive 7-candidates, proving aqua.

Now follow this color collapse: Removal of tan leaves orange = blue by 7-candidates in r4, merging clusters.

Blue/green color trap =>S6, which proves blue with the last 5-candidate in r8.

Addicts 126 UR ERXYZThat was quite a show,  but Stephens’ Extremes have more.

For next time, see what you make of this.  It’s a mystery snapshot from  the Addicts  review puzzles.  Write yourself a note explaining exactly what is going on.  I’ll open Stephens Snapshots II with my  take on this event.

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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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