Doubt regarding the physical folding of a two dimensional K-map

While grouping terms in a k-map, if we pair terms on the first row with the ones on the last, it can be interpreted as the folding the 2-D map in the form of a cylinder, along the horizontal axis.

Similarly, if we pair terms on the leftmost column with the ones on the rightmost column, it can be interpreted as the folding the 2-D map in the form of a cylinder, along the vertical axis.

But when we group the four terms to form a quad, each on the corner, what does it physically mean?

• (Geometry is not physics. And that there is a helpful "visualisation" in one case or two doesn't mean there always got to be one, or that any given one needs to carry into even the "next higher dimension" - try using a Karnaugh-map for seven variables. That said, take a, say, table tennis ball, draw three perpendicular Great circles and use for three variables. Draw the four variable one on gelatine, soak, place it on a ball. Pull the corners to meet opposite the original centre. Close the gaps and digest which (groups of) areas are neighbours.) Sep 9 at 7:17