  To construct the Smale horseshoe map (Figure 2), start with the unit square (indicated in yellow). First, stretch it in the \(y\) direction by more than a factor of two. Then compress it in the \(x\) direction by more than a factor of two. Now, fold the resulting rectangle and lay it back onto the square so that the construction overlaps and leaves the middle and vertical edges of the initial unit square uncovered. Repeating these stretching and folding operations leads to the Samale attractor.