Operators on a cube
Since there are no rows, the only possible operator on data in a cube is selection. Contrary to the relational case, this operation affects metadata as well. This is one of the properties of the multidimensional algebra:
all of the operators change metadata, directly or indirectly.
One more thing to note: here we restrict our consideration to a certain class of cubes. Although in order to solve a specific problem we have developed a multidimensional view of the world, it is artificial. Therefore we do not require immediate adjacency of particular cells in the grid. However, as we further refine the model, certain proximity of cells may be needed.