This is just a verification of Insights No. 2
(b) RASHI (77b, DH she'Shelivosav) does not accept this reasoning. He maintains that a ledge diminishes the height of a wall even when the ledge is four Tefachim in only one dimension. How, then, does Rashi answer our question?
I looked at this Rashi several times on 77b near the bottom of the Amud. The ledge is on the next Amud. In fact this Rashi doesn't seem to
mention anything about dimensions, unless it's connected to the next one which is discussing a ladder.
PS I found both Insights very informative, helpful, and enjoyable.
Thank you for your correction. The correct DH should read "Im Yesh" (the above quoted Rosh seems to clearly deduce Rashi's opinion from this Rashi).
A Freilichen Chanukah,