When [a sukkah is more than twenty cubits high, but] one builds a bench next to the middle wall extending across its entire span - if the width of the bench is equal to the minimum width of a sukkah, it is kosher.
Should one build the bench next to the middle wall along [one] side, if there are four cubits between the bench and the [opposite] wall, it is unacceptable. If there are fewer than four cubits, it is kosher.
Should one build the bench in the middle [of the sukkah], if there are more than four cubits from the edge of the bench to any of the sides [of the sukkah], it is not acceptable. If there are fewer than four cubits, it is kosher. It is considered as if the walls touch the bench, and the distance from the bench to the s'chach is less than twenty cubits.
If one constructs a pillar [within a sukkah whose s'chach is more than twenty cubits high, the following rule applies]: Even though it is of the minimum size required of a sukkah, it is unacceptable, because its walls are not discernible. Thus, it is as if there is kosher s'chach above the pillar without any walls.