[ The Types Forum (announcements only),
http://lists.seas.upenn.edu/mailman/listinfo/types-announce ]
http://arxiv.org/abs/1303.5039
Abstract.
Contexts (environments) are not sets or lists without multiplicity, but
have a more complicated structure. There is a natural order on the set of
contexts. A "set" of free variables is not a set, but a context in the new
sense. New definitions simplify working with explicit substitutions.
It is desirable to see this article (Lang and Lescanne) before
http://lara.inist.fr/handle/2332/734
