HM Easter Monster Solved

This post finishes the HM Easter Monster with Sue de Coq, X-chain ANL, coloring trials, and a remote pair. It ends with a summary of the Hanson and Marans review

HMEM red startIn the last post, trials of blue and green wrapped orange, and we now know the red candidates are true. I’m going to big red clue numbers, because this is no longer on trial.

The blue/green expansion begins with the 3r4c9 trap. Then 3r3c5 turns green, trapping 3r1c6. Simultaneously, 3r7c9 turns blue, trapping 3r7c8.


HMEM 3 chain swordTwo very ordinary advanced techniques have a say, a 3-chain and an easy swordfish.

In c8, I verify Sue de Coq SEc8 = 1(2+9)(6+7) with victim 7r5c7 by showing that a naked pair in SEc8 rejects both blue 3r7c9 and green 3r6c5. The forcing chain from 7rec7 to 3r6c5 is has an ALS node, 367r6c78.

That is one fancy color trap! It turns 7r5c9 blue, trapping 7r3c9 in the ordinary way. From there, blue/green expands by seven traps!

HMEM red SdCThe expansion traps 5r5c6.   SdC Wc3 = 7(1+5)(2+8)+751 is verified. First, 1r6c3 removes 1r4c2, turning 1r4c6 green, and trapping 5r4c6. This enables a forcing chain from 5r5c3 to confirm 5r2c4, rejecting green, and 5r1c2 rejecting blue. So Wc3 can’t be 751.

The SdC removes 28r4c2. As it turns out, this removal really simplifies the blue color trial coming up. A bonus is that 5r4c5 can also be removed. If true, it reaches the same contradiction.

HMEM red blue trialThe blue trial is very simple. Three blue candidates and four forcing chains confirm two 5’s in r1. So the green candidates join the red ones as clues.







HMEM final traceAs you might expect, the EM Monster shows some resistance even here. The regular 2-D trace dies, and we look for an opening for a final blow.

HMEM remote pairNot hard. There is a long series of 29 bv and a quite evident and adequate remote pair to finish it.

There has been a surprising amount of discovery in our review of Hanson and Marans web article on HM Easter Monster. I applied Steve K’s reasoning to another form of the EM.

For everyone, there is an interesting contrast in extreme methods between the HM strong link chains with the undisclosed ALS pair eliminations, and the Sysudoku pattern analysis with advanced Sue de Coq and Medusa coloring. Finally, in the wrap up trials, there were new forms of color trap via forcing chains and pattern analysis. Although our solution followed the plan of the Hanson and Marans attack, it was not endorsed as a human campaign strategy against monsters.

After three – or perhaps you count only two – monsters, let’s take a break, and go to school. We’re going to take class with Bob Hanson, one of the authors of the web paper just reviewed. Maybe we’ll learn more about Almost Locked Sets.



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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