Almost Extreme Bean ExHdv10 II-29

Here we have a regular XYZ wing with two irregular victims, multiple coloring clusters and wraps, one, by an AIC almost nice loop. Rebecca Beam’s Extremely Hard v.10 II-29 is borderline extreme.

Basic is tough, but routine.


Except for the 4-wing as line marking begins.


Line r7 was filled in box marking with a match occurring on the r2, the first line marked. The wing fins stay in place as the remaining lines are marked, prohibiting the entry of 4’s in columns c2 and c6. To report what happened, I put them in and mark them as removed.



The 4-wing removal enables two naked triples, one in the North box and one in c6. The latter triggers a 9-boxline, and a 67 subset in c4.







The growing bv field produces a rectangular XYZ-wing, which yields nothing to unit winks. Here two victims look around the ER corners to see two of the three members of the wing’s toxic set.


When a target is suggested, you can often construct a chain to see it.

With coloring, II-29 begins to  look more extreme.  Coloring breaks the bv into three disconnected clusters. When AIC hinges are added, an AIC ANL wraps orange with a trap in r2c7.




One wrap leads to another, and another, in the collapse of Extremely Hard v.10 II-29.


At this point I’ve completed the remaining review puzzles, and can share the review table for Rebecca Bean Extremely Hard v.10 with you.

Next is one of the two Sysudoku extreme rated puzzles of the ExHd v. 10 review, way down at a Moito rating of 0.93.  It is VI-24. From me it demanded coloring trials. Maybe you can do it straight up. Notice how I’m assuming the Moito and Bean ratings are the same. Where’s the explanation of either or both?

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The Volume 10 Rebecca Bean Extremely Hard Sudoku

This post begins the second review of a Rebecca Bean collection, this one prompted by a clever cover, and similarities in format to recently reviewed collections attributed to Moito Publishing, A.D. Ardson and James D. Glover. Here we resolve Extremely Hard v.10 I-34, assigned last week for your homework.

In my first Bean review, of 600 Extremely Hard Sudoku Puzzles with Answers, there were 12 sections of 50 puzzles each.  I selected the #6 puzzle from each section. There were only two advanced puzzles in that selection, and nothing extremely hard. Later I reviewed Moito’s Sudoku Road to Mastery, which proved to be much more challenging. The grids of the Moito, Ardson, and Bean books are identical. None of them provide any background accounting for the similarity of production or anything else.

But significantly, Moito and Bean ExHd v.10 share something else, a rating system covering an identical number range. The system also appears in Glover’s unacknowledged Sudoku Puzzles Evil Killer.  In the Moito review, I selected 10 highest rated puzzles, and therefore have reason to believe that doing the same with Bean v.10 would produce a fairer evaluation.

One more bit of context before we plunge into Bean’s ExHd v.10. A look at Bean’s Amazon author page reveals over 50 collection books carrying “Extremely Hard Sudoku” in the title! And I thought the “volume 10” was a promotion device!

Many have clever covers, but there is no statement inside about duplication. I found one match between my two ExHd’s by picking one and scanning the other book for a duplicate. Also, in view of the deluge of similar books,  I’m not persuaded that  Rebecca Bean and A.D. Ardson are people. Could they be computers in a Moito back room?

Representative or not, the two Bean reviews and two Ardson reviews will be my last, unless readers have reason to suggest otherwise.

Now for Extremely Hard I-34, Bean rated 0.94. The basic trace is typical of the volume 10 collection: resistance to the bypass, normal box marking, and a tough line marking.

The Sue de Coq chute  is described by   SEr9 =8(6+9)(1+7) with a removal in each remainder.








On the 3-panel, a grouped 3-chain ANL reduces the fins of a swordfish to one, and the fish removes a 3 in the fin box.

The removal leaves a decisive boxline. See it?





Yess! 3r6c1 goes as well, setting up a naked pair that takes five 9-candidates with it.








Then more X-chain ANL, one on the 6-panel, and one on the 8-panel, bring the collapse.

Advanced, but not extremely hard. Did you do it that way?





Next week, it’s another 0.94 but tougher, with a special WYZ-wing and a heavy dose of coloring. Its Extremely Hard v.10 II-29.

There are new pages off Sysudoku Advanced in the Guide. One’s on unique rectangles and other uniqueness methods. Off the BV Scan, there’s a new one on Sue de Coq. The Sysudoku approach differs from expert consensus in a fundamental way.

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An Unexpected Challenge from TV Times

Sysudokie Sunday breakfasts were shaken up February 4 by the Sudoku in the TV Times, which unaccountably defied the bypass. Accustomed to dusting this one off as a warm up, many wound up with an unwelcomed cloud on the amply sized grid, and spending surprising amount of time getting to a solution.

Forget about 3-fills. Starting with the grid in the previous post, the scan of numbers produces a trace of

SW1, C9,

and this grid.

Now you have to recognize that the c5 5-fill gives a hidden single 8.  Put that in and rescan 1 – 9, for three more clues.


  Here is the trace, . . .


. . . and the grid at the naked single point of collapse.  Who would’a thought?








We’re spending some in March with Rebecca Bean’s Extremely Hard Sudoku, v.10, and you’re invited to the preview, with her second highest rated puzzle I-34.

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Ardson’s Toughest, Even Slightly Diabolical, 310

This post fleshes out the review table entry, and checkpoints the two week homework assignment of the Ardson Sudoku Diabolical v.1. The early coloring typical of the review is helpful, but not decisive.

In the bypass, the 3-fill menace is resisted, and there are two very unsystematic hidden singles you are forgiven for missing, 4r4c3 and 8r4c7. You may be mystified until you see the causes in the trace. Now I don’t know how I spotted them.




The remainder of basic is routine.





With no grid scanning prospects, the North bank bv field looks ripe for coloring.  A cluster is started, yielding a trap that nets naked pair N15, expanding the cluster.

To follow up on that, I added two more limited clusters, but return to systematic city with the XYZ map


A right angle XYZ is usually useless, but this 381-wing shows that in the AIC seeing world, the right angle is a plan for a construction project. Just look for a potential victim seeing two Z’s, and see if it can possibly see the third one.

You’d never search for such an AIC without a specific target.



The added clusters come with possible bridges:

In c4, not(orange and maroon) => red or grey.

In r7, not(blue and orange) => green or red.

On the 1-panel , a finned swordfish extends blue/green, and sets up a coloring bridge. In r6c3,

not (green and grey) => blue or maroon.

That bridge traps 1r9c1, expanding maroon/grey, . . .




. . . into the South box, where another bridge emerges:

not(grey and orange) =>maroon or red

=> red and

(maroon or grey)

=> red.




The resulting maroon/grey expansion wraps grey in the South box.

Then maroon wraps blue.

That pretty much wraps up Diabolical 310 and the review. If it really takes the irregular 381-wing, the finned swordfish and the multiple wraps, I’ll concede that diabolical puzzles can be found in A.D. Ardson’s Sudoku Diabolical v.1 .

Next, we detail the solution path for the 2/04/18 Sudoku in my TV Times magazine. It’s basic level, but may have generated complaints from readers unable to get a toe hold on a Sudoku they are accustomed to solving. For me, box marking revealed two inferences it takes a more talented  sysudokie to spot in the bypass. Are you one of those?

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The Bypass 3-Fill Smacks Diabolical 350

This post starts with a trace of the merciless 3-fill pounding of Ardson’s Sudoku Diabolical 350 in the bypass. Highlight grids from adv2 110 and 190 then follow.

The 3-fill brings on the unit fill phase of basic solving, when fills take precedence over number order, much sooner. The challenge is to avoid overlooking 3-fill opportunities. Writing out the 3-fill strings in the trace is effective for me, but you may find that I have overlooked a few.

 After the effects of NW1 are explored, the main list resumes with N3.

 Here is the grid near the end of the first leg, after C3. Single pencil marks indicate effects not yet explored as causes.







Diabolical 110 offers another kind of highlight, a near-BUG right out of the bypass. Filling in the 3-fills where possible, and coloring, you get traps and a blue wrap in the SE box, and a green solution.




In case you’d like to watch this happen, here’s the basic trace.




Sudoku Diabolical 190 is also reduced to a bv sandbox by the 3-fill. After these bypass actions,

and easy box and line marking, 190 is vulnerable to the two bv predators, XY chains and coloring clusters.

First, two XY- chains make three removals. One is removed by boxline as well.








Then coloring is decisive as two blue candidates are forced in r4c2.

Next week, a full backup of your solution on Sudoku Diabolical 310. In this review, it’s saving the best for last.

Be kind to your Valentine.

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A.D. Ardson’s Sudoku Diabolical

This post begins a brief review of A.D. Ardson’s Sudoku Diabolical, with a review table and analysis of the first of a pre-selected series 30, 70, . . . , 390. Ardson’s Sudoku Very Hard Puzzles, volume 2, very similar in format, was reviewed in April through July of 2017.

In comparison to Very Hard v.2, Ardson’s Diabolical v.2 appears from my sample to be less consistent, and certainly not more diabolical. Four of ten collapse in basic, two in the bypass.  Among the advanced level puzzles, a generous bv field invites coloring, and with consistent success.

Your homework, Dbv1 30, got the Diabolical review off to a good start with me. The 3-fills made a big splash in the bypass, and line marking featured a nice naked triple, and an 8-wing at the end of the close.


The 8-wing in two columns is not available until all rows are marked. It is spotted in closing as the c7 8-slink gets marked, and the other columns are scanned for a matching slink. It’s a sysudokie bonus of line marking

Besides coloring, another benefit of a generous bv field is an extensive XY railway. Here, three XY chains yield five almost nice loops (ANL), one for each victim.

After this, there is not much for the X-panels to work on.

But coloring is well supported, and the first cluster has four traps. Among them, the 5r7c1 removal creates r7np37, removing a green 7, wrapping green.




As blue dominated dbv1 30 fights on, a new cluster is added. The modified XY railway nets two ANL to  wrap red, for the orange finish.

Next, a trace of the bypass collapse of Sudoku Diabolical 350, a showpiece for the 3-fill.

Try it out. The starting grid is at the end of the Guide page Begin with the Bypass.

Also next post,  I’ll have highlight grids from dbv1 110 and 190.

The Diabolical review will conclude with a full report on dbv1 310. Shown here. You have two weeks to mull it over, then compare details.

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Coloring Bails Out Basic on III-34

In this last post of Moito’s Sudoku Road to Mastery, Basic drives the 0.91 rated III-34  into a near BUG blind alley with a flurry of subsets and boxlines, then hands off to coloring for a quick score.

A tight bypass resolves one 3-fill and leaves one. Then box and line marking go routinely until I prefer two 7f: final rows over a gaggle of columns, and finish the rows on r6.

The grid at that point  has the first subset, a modest naked pair. The pair removes four 8’s, but one of those removals brings more than a clue.





What happens is that C4 removes 4’s to create naked quad in r4 and a naked pair in c3.







The quad generates two boxline slinks, but the naked pair starts a collapse, which . . .



. . . stalls one cell short of a BUG. But no problem. Coloring reveals in c8 that green is impossible.








Next post begins a review of A.D Ardson’s Sudoku Diabolical, with # 30, shown here. Let’s compare solutions.

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