SUDOKU TERMS - A GLOSSARY

Maybe you've got your eye on this new date and he/she is into sudoku so you want to impress... or perhaps you just want to know more about this quirky mathematical puzzle... either way - here's an overview of the terms and facts about sudoku  so that you can  impress that cute girl in accounting or the hot guy in payroll :)

Terms associated with the grid layout and puzzle

A grid has 9 rows, columns and boxes with each having nine cells. A full grid has 81 cells. Cells are  called squares, but in technical descriptions (for example if you should make it through to the World Championships)  the term square is avoided since the boxes and grid are ...wait for it...also squares!

Boxes are also known as blocks or zones and 3 vertically stacked blocks make a stack. Three horizontally connected blocks however  make a band. A chute is either a band or a stack. A grid has three bands, three stacks and six chutes.

The use of the boxes to partition the grid can be generalised to other equal-sized partition shapes, in this case the sub-areas are called regions, zones, subgrids, or nonets. In some cases the regions are only equal sized, not equal shaped.

Rows, columns and regions are collectively referred to as 'units' or 'scopes', of which the grid has twenty-seven. The 'One Rule' rule  is that 'Each digit appears once in each unit'.

Size refers to the size of a puzzle or grid. Often a composite row × column designation is used, e.g. size 9×9. In technical discussions (should you end up on the Sudoku consultative committee at the World Championships!)  size may refer to the number of cells, (81). Since the number of cells in a region must be the side dimension of the square grid, for example  nine cells per block for a 9×9 grid, it is convenient to just use the region size, such as 9.

Puzzle terms

A puzzle in essence  is a partially completed grid. The initially defined values (the numbers already inserted)  are known as the givens or  the clues. A proper puzzle has a single (unique) solution. A proper puzzle that can be solved without trial and error (guessing) is known as a satisfactory puzzle - don't ask me why!

An irreducible puzzle (also known as a  minimum puzzle) is a proper puzzle from which no givens can be removed leaving it a proper puzzle (still with a single solution). It is possible to construct minimum puzzles with different number of givens. The minimum number of givens refers to the minimum over all proper puzzles and identifies a subset of minimum puzzles.
Know you know a bit of the glossary terms associated with sudoku - you can talk sudoku like a pro with the pros :)