Erasable Games Weblog

(Sudoku in words and pictures)

Archive for June, 2007

Subset Sudoku

Sunday, June 24th, 2007

Subset Sudoku

This Sudoku variant supplies the correct triad locations of the numbers of the solved puzzle, but offers far fewer starting numbers. Even so, the puzzle is solvable when considering the subset of candidates that can be in a particular cell.

I found a math site called cut-the-knot.org that shows how you can intersperse only plus or minus signs to the fixed sequence of digits 1 2 3 4 5 6 7 8 9 so that the resulting arithmetic expression, when simplified, is 100. It’s both harder and easier than you think! Likewise, the sequence 9 8 7 6 5 4 3 2 1 is also considered for expressions results simplifying to 100.  There’s more than one, but not many.

Odd Sudoku

Sunday, June 17th, 2007

Odd Sudoku

I had to skip a week due to superceding short term tasks to complete involving a Linux workshop I conducted last week.

This Sudoku variant supplies the correct odd/even location of the numbers of the solved puzzle, but offers fewer starting numbers. This encourages constraining logic when considering the possibilities of each cell.

A discussion of Odd and Even Numbers is offered in Wikipedia.

Jigsaw Sudoku

Saturday, June 2nd, 2007

Jigsaw Sudoku

Jigsaw Sudoku relaxes the requirement of square blocks as in regular Sudoku puzzles. Instead, non-square rectilinear shapes made out of contiguous cells are used instead. The requirement that rows and columns each have unique digits is still true, however.

Some sites that offer Jigsaw Sudoku puzzles include: Puzzle Club, Competition Jigsaw Sudoku and a site offering Sudoku Variants And Other Number Placements.