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A "board" is therefore a set of three {{Vector<ICellSet>}}s Vector<ICellSet>s representing the rows, columns and blocks of the board. Note that any given cell will appear once in the rows, once in the columns and once in the blocks. The data structures that we have created enable us to access the cells in multiple methods that clearly represent the cell relationships in the manner that best models the problem at hand, namely the Sudoku board. We can easily and consistently see the cells in terms of rows or columns or blocks in a manner that is abstractly equivalent, enabling us to easily reuse the same code to process the cells in any direction we choose. Compare this to a standard NxN matrix representation (a collection of rows) which represents only a single cell relationship feature, namely that they are in rows. Luckily, accessing the cells in terms of columns is not too difficult, but accessing them in terms of blocks is a bear!
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