Sukkah 4: From the Earth to the Heavens

More on the very tall 20+ amot high - what if you build a platform within it, raising the ground, as it were, so that it's less than 20 amot high on the inside? In what ways does this work to make the sukkah kosher? (via a few different cases, including some with a curved wall, no less). Also, what about a very small sukkah? Then you want more sunshine than shade, to make sure the shade isn't from overhang schach. Plus, other cases of size adjustment - specifically, digging down, so a less-than-10 tefachim high sukkah would end up at least 10 tefachim. Plus: R. Yaakov's radical sukkah. Also, the Gemara's emendation of R. Yonatan for R. Yochanan (in Seder Moed). And finally, where is the 10-tefachim measurement from, as a minimum?