The Big Sudoku Brain Workout by Tom Sheldon
reviewed by Mary Whipple
Believing that the "occurrence of neurodegenerative disease is less marked in people who have busy and varied lifestyles"--i.e., those who keep their bodies AND their brains active--Tom Sheldon, author and expert in "bioinformatics" and artificial intelligence, has devised a book of one hundred fifty "puzzles for a younger mind."
While people are not stopping me on the street to exclaim about my "younger mind," I can attest to the fact that these are terrific puzzles, a great way to fill odd moments of time--those periods too short to read. For those unfamiliar with sudoku, each square puzzle consists of a grid containing nine squares, each of which contains nine small boxes within it--81 boxes for the whole puzzle. The objective of the puzzle is to fill in the boxes so that each horizontal line of overall puzzle contains the numbers 1 - 9, each vertical column contains 1 - 9, and each of the nine squares contains numbers 1 - 9. Some numbers are given in advance so that puzzler can use them to build on, the easy puzzles containing more given numbers than the "fiendish" ones.
The book is well designed. Approximately 5" x 8" in size, each page contains only one large puzzle, providing plenty of space for writing numerical possibilities into each square on the more difficult puzzles. Four levels of difficulty and an introduction containing helpful hints for solving puzzles provide plenty of options for the beginner, and the most difficult level will challenge even the seasoned sudoku fan. An answer key is in the back of the book, especially helpful for the beginner who may want to check some decisions as s/he goes along.
With a binding sturdy enough to permit folding the book in half to work on the puzzles on the left side, the book is inexpensive and easy to tote around in purse or briefcase. A few pages of blank forms would be helpful, and some might prefer a spiral binding, but this is a terrific book, and few fans will quibble about those minor issues in view of the puzzles' excellence.
Sudoku Genius by Tom Sheldon
reviewed by Mary Whipple
Tom Sheldon's second book of sudoku puzzles picks up where the introductory Big Sudoku Brain Workout leaves off, presenting 144 difficult puzzles graded in nine levels of difficulty, from Daunting to Deadly. Though these are described as "the most fiendish puzzles ever devised," they can all be solved (albeit on the second or third try, sometimes) by someone who has a basic knowledge of sudoku strategies and a good sense of logic.
I began at the beginning, and either there is not much difference between the puzzles from the beginning to the end or I learned some tricks as I went along, but I found myself spending about the same amount of time on the puzzles at the end as at the beginning. Some of this may be because I gained greater practice using some of the techniques Sheldon includes in his helpful Master Class in Advanced Strategies, in the introduction.
The author helpfully lists the thirty puzzles which require "trailing," his term for the technique that is sometimes necessary when groups of pairs block further progress in solving the puzzle. He makes a case for why this controversial technique (which involves choosing one of the numbers in a pair at random and following it throughout the puzzle) is still logical, not simply trial and error. He didn't convince me, but the puzzles could easily solved (especially when the first trial number was done on a Xerox copy). Several intriguing puzzles are completely missing one given number, but those turned out to be the most fun, and, as a rule not diffucult. Some not listed as requiring trailing did require it, and three or four listed as requiring trailing did not. and one puzzle, done by both my husband and me, turned out to have two completely different and correct solutions!
The book is a good size, easy to carry in purse or portfolio, and the extra grids are helpful is you don't have a Xerox machine handy for copying the puzzle as you have worked on it to date. The puzzles are large, with plenty of room for listing options, and the answer key is at the end. Overall, this is a terrific collection for the sudoku puzzler who doesn't want to spend all day on one puzzle, a collection of challenging puzzles which are still "do-able."
Sudoku Master Class by Tom Sheldon
reviewed by Mary Whipple
My introduction to sudoku was Sheldon's Big Brain Workout, a book which guides the beginner from easy to more difficult puzzles. Sudoku Genius continues the series, with difficult puzzles representing the "nine circles of hell," from Daunting to Deadly. Sudoku Master Class introduces advanced strategies for solving the most difficult puzzles. For the first twenty-four puzzles, the answer key provides guides to the techniques discussed in the introduction--including X-wing, swordfish, and various buried partnerships, so those experimenting with new techniques may want to check the hints in the answer key first so that they can practice these techniques.
Like the other books in the series, the puzzles themselves are large, with plenty of space to record options, one puzzle per page. The books, about five inches by eight inches, fit nicely into a purse or briefcase, and though there is no spiral binding, the fixed binding still allows for right-handed puzzlers to have plenty of space to work the puzzles on the left side of the book. Though all these puzzles are supposed to be difficult, some are much more difficult than others, and I found myself wondering, after a particularly difficult puzzle, if the author deliberately made the next puzzle much easier, as was so often the case.
Three puzzles (#57, #64, and #130) are missing one number from the outset, and while these may appear difficult, they are, in fact, the most fun of all the puzzles, and not difficult at all. I confess that as I was practicing techniques at the beginning of the book, I sometimes got stuck and had to resort to "trailing," Sheldon's word for choosing one number from two pairs and tracing it through the puzzle to see if it is the correct choice. Gradually, as I became more proficient at some of the techniques, the amount of trailing declined so that by the end I was not doing it at all, the sign that Sheldon has created good puzzles which rely on logic, rather than chance.
My appreciation of this series has grown since I tried to find a comparable new collection at the local bookstore--Sheldon may be unique in his grouping of puzzles of comparable level of difficulty in a single book. (Most others contain a range from easy to difficult.) I'm crossing my fingers that Sheldon has another collection in the works.
Jumbo Sudoku Challenge by Michael Mepham
reviewed by Mary Whipple
What makes this sudoku collection really special is its fascinating variety! Omitting the Easy and Medium sudoku, the collection begins with regular "Hard" puzzles (88 of them, not too hard), and then moves to Fiendish, seventy-seven of them. (Tom Sheldon's Master Class has more difficult "fiendish" puzzles, but the ones here are fun, too.)
Then I discovered variations that I'd never tried, each of which provided hours of new fun! Samurai Sudoku was my first variation--five connected sudoku with a center puzzle sharing its corners with four additional, interdependent puzzles. (See cover photo for example.) It is necessary to use patterns in the additional puzzles to fill in the center puzzle and, most importantly, its shared corners so that the other puzzles can all be completed. Fortunately, author Michael Mepham rates these from Easy to Fiendish, as I found these puzzles initially to be quite challenging.
The Jigsaw Samurai Sudoku have become my favorites. Similar to regular samurai sudoku, the center puzzle has square corners, requiring 9 numbers, but except for these corner squares in the center puzzle, there are no other squares. Where the squares would be are irregular shapes, some of them in crosses (using one column and one row), some looking like stair steps through the puzzle, and some looking like the NYC skyline. The challenge is to give each irregular shape each of the numbers from 1-9, while, at the same time, putting 1-9 into each vertical column and each horizontal row. These range from "easy" to "fiendish."
Twelve by twelve and sixteen by sixteen square puzzles, which require numbers from 1-9, in addition to letters--A-C for the 12x12, and A-G for the 16x16 are all ranked "hard." The last variation, "Killer" sudoku, shows irregularly shaped "cages" within the regularly-shaped squares, each cage containing the mathematical totals for 2, 3, 4, or 5 numbers within the boxes they enclose. Only a few numbers are shown in the boxes(usually two or three, on average) and one "fiendish" killer puzzle, offers no given numbers at all, only the totals in the cages. Varying from "easy" to "fiendish," these require simple math.
My minor problem with the book is its binding--a spiral binding would help right-handers do the puzzles on the left side, especially at the beginning of the book. (I ended up Xeroxing some of these left side puzzles because it was hard to write along the tight binding.) The pages are 8" x 10 1/2", however, and offer large boxes and plenty of room to write. The paper quality is very high, allowing for numerous erasures. A great collection offering weeks of fun and many new puzzle experiences!