KrazyDad Super-Tougn 515 Starts a Review Update

This post begins the update review of the Super-Tough collection available on with volume 5, book 1, number 5.

The Super tough collection was first reviewed in March 2013, but that was one of the first reviews on Sysudoku, and only four posts were devoted to it. That review is updated here, with the full basic trace and all significant diagrams. The KrazyDad Insane collection is also reviewed on Sysudoku (see Titles). Both Super-Tough and Insane are huge collections, 20 volumes of 100 books, each with 8 puzzles.

My KDST 515 bypass starts with two 4-fills. In c2. NW1 and S1 together see three cells, leaving one for W1. You probably see the 5 clues in c2 first, then note the missing values 1456, then look for one of them boxed with two free cells. Find the second 4-fill, and confirm it in the basic trace.

On the line marked grid, a naked pair 28 signals a possible unique rectangle. With a floor to ceiling slink, the opposite rectangle candidate in the ceiling has to go.  It 8r5c5 is true, so is 2r2c5 and 8r2c4, making 2r2c4 false. The slink makes 2r5c4 true. Rectangle values 2 and 8 can then be interchanged for a second solution.

A second boxed naked pair gives up a second hidden rectangle of the same type. Same rule. Trace this one out.

Two clusters cover most of the bv. They are bridged in c9 by

not(green and orange) => blue or red or both.  

Beeby finds a 1-way that expands the blue/green cluster to a second blue 3 in r6. Green then wraps orange r9c9.

A second way to wrap blue and orange is this  AIC  ANL with two green terminals. Absent the blue victim seeing both terminals, blue is wrapped because at least one terminal of an ANL is true.

But these are AIC building moves.

By construction, and much easier is, in the bv scan,

using the Sue de Coq restrictions of

 Cr5 = 2(3+8)(5+6)


Cr6 = 1(3+9)(5+6)

to show that

blue =>  9 in Cr6

=> 3 in Cr5

=> 5 in CR6

 => orange, merging the clusters

Then a couple of lite traps wrap blue.

 First, 4r3c2 blue lites 3 r3c5, trapping 3r7c5. That allows 4r7c1 to blue lite 8 r7c5, which blue lites 8r2c4, trapping 8r4c4. In c4, C4 does the wrap.

Collapse is just as immediate.

For the volume 5, book 2, number 5 puzzle we do next week, see


About Sudent

I'm John Welch, a retired engineering professor, father of 3 wonderful daughters and granddad to 7 fabulous grandchildren. Sudoku analysis and illustration is a great hobby and a healthy mental challenge.
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