Mark writes:

“This tattoo is the Zermelo-Fraenkel with Choice axioms of set theory. These nine axioms are the basis for ZFC set theory, which is the most commonly studied form of set theory and the most well known set of axioms as well. From these nine axioms, one can derive all of mathematics. These provide the foundation of mathematics, a field that you can likely tell that I love dearly.”

Carl: Mark is making an encore appearance at the Emporium. See his Y combinator here…