  The Mizar Mathematical Library (MML) is a rich database of formalized
mathematical proofs (see http://mizar.org). Owing to its large size (it
contains more than 1100 "articles" summing to nearly 2.5 million lines of text,
expressing more than 50000 theorems and 10000 definitions using more than 7000
symbols), the nature of its contents (the MML is slanted toward pure
mathematics), and its classical foundations (first-order logic, set theory,
natural deduction), the MML is an especially attractive target for research on
foundations of mathematics. We have implemented a system, mizar-items, on which
a variety of such foundational experiements can be based. The heart of
mizar-items is a method for decomposing the contents of the MML into
fine-grained "items" (e.g., theorem, definition, notation, etc.) and computing
dependency relations among these items. mizar-items also comes equipped with a
website for exploring these dependencies and interacting with them.
