More Oznottery

I am certainly one to defer to my classmate Paul Kolodner in technical matters, but an error must have slipped into his April 25 letter in Inbox. In the context of some continuing Oznottery (“The Oznot Project,” feature, March 21), he mentions that he and his roommates reasoned that “the null set is an element of all other sets.” He doubtless meant that the null set is a subset of all other sets. I shouldn’t have mentioned the point except for my fear that current undergraduates might be looking at the letters column and basing their subsequent beliefs in set theory on what a sage alumnus had to say.