Tom Sheldon deserves a lot of credit, or blame if you prefer,  for introducing me to serious Sudoku solving.  I pored over the instruction section of his puzzle book, Sudoku Master Class, intrigued by the very idea of a master class. I marveled at his locked set rules and his grandly general fish theorem.  So Tom’s Master Class collection gets my first grading review.  Here I will concentrate on the puzzles.  In the next post, I will review Sheldon’s recommendations for solving.

Master Class came out in 2006, a year earlier than Stuart’s The Logic of Sudoku.  Mine  is a soft cover  book with 144 puzzles, beginning with 14 pages introducing solving methods.

In SSOB grading reviews, I will report how the survey puzzles fared in the two stages of basic solving, and in advanced solving. I will mention the techniques that  generated removals or new clues.  Ten puzzles are taken for the survey, by a predetermined rule.    I started the survey with Master Class #30, avoiding the “apprentice” puzzles, and selecting every 10th puzzle.

Before plunging into the review table for the first time, you may want to consult the Reviews page for an explanation of table coding.

To interpret the tabulated Master Class survey results, you need to know that the only advanced methods that Sheldon presents in his instruction pages are regular fish, and the simplest “Type 1” UR.  Nevertheless, Tom claims that “Having mastered these, you will be ready  to begin working your way through some of the hardest puzzles you’ll ever come across.”  Was Tom serious? My sysudokie readers realize that the advanced techniques of Master Class are seriously  limited.

But regardless of the hype, how difficult are the puzzles?  Most succumb in line marking, but after a quite reasonable basic solving workout.

So far, I have to take exception to another Sheldon claim, that, ”All the puzzles in Sudoku Master Class can be solved using the techniques I’ve described, without resorting to any guesswork.”  In the survey of 10, two puzzles, numbers 60 and 90, seem to require methods that Master Class omits.  Master Class describes the UR problem, but nothing on UR analysis. It has nothing on Sue de Coq, XYZ-wings or AIC of any kind. I checked to see if a regular fish would work in the absence of these and after basic solving, but found none.

Also associated with this claim of puzzle covering instruction is the matter of unique rectangles we have been exploring , in which Tom describes  the simplest form of UR, but the puzzles require much more advanced UR technique.

True, there is no standard among Sudoku collections to have the puzzles stay within the explanations. Far from it.  But I have to call out the failure to deliver on the above claim as a breach of trust.  It makes me think that the other Sheldon claims are not in good fun, either.  Can a Sheldon devotee please vindicate Tom and find Master Class methods for every review puzzle?  If so, I’d be delighted to publish all firsts in this blog, with thanks and full credit to their efforts.

Bottom line on the Master Class collection’s level of difficulty, it is line marking solving level, except for UR, and occasionally, getting into other bv scan techniques and regular fish.  Fishing rarely gets above X-wings.  This leaves most advanced methods out. It is therefore pretentious and misleading to call this book a master class.  From Tom’s instructional philosophy and his comments in the forward of Master Class, I expect that his earlier work, Sudoku Genius, is similarly limited.

Although Master Class is a worthwhile collection for its level, I must admonish Plume Books for the overblown promotion. A breathless testimony on the back cover gets my tickle bone, though.  “Start with a Sudoku refresher course in basic rules and techniques before moving up to methods formerly only whispered about in the halls of the mathematics department. “

Back in the real world, Master Class #70,was suggested for box marking in the previous post. Here is a 2D trace of the box marking, followed by the resulting grid.

You can tell what is in store in line marking from the review table entry.

I hope you steered clear of that  “almost naked triple” that looked so obvious in box marking. Now let’s do some line marking.  This is an example of how you might use these reviews.  You can try to correct  me in the grading of the review puzzles, and if so, you can send me traces for recognition in the blog, Of course you have to buy the book to get all of the reviewed puzzles, but why not? Puzzle makers gotta eat.