Metamath is a tiny language for expressing theorems in abstract mathematics, accompanied by proofs that can be verified by a computer program.

This package contains a number of Metamath databases developed collectively by people from the Metamath project, including set.mm (Metamath Proof Explorer) and others available at http://us.metamath.org/.

You can edit and verify these databases with any tool implementing the Metamath language, including the reference implementation available in the package metamath.