Cutting and stacking
= Cutting and stacking
Cutting and stacking constructs <measure-preserving transformations> from towers of equal-measure levels. Cut a tower into equal-width subcolumns, add new spacer levels, and stack the resulting columns. Map each level to the one above by a measure-preserving identification; subsequent stages extend the partial map. When uncovered and top-level measures tend to zero, the limiting map is defined modulo null sets.