  We present a new lambda-calculus with explicit substitutions and named
variables. Renaming of bound variables in this calculus is explicit (there is a
special rewrite rule) and can be delayed. 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
alpha-conversion.
