Set Theory and Elementary Algebra in LEAN 4 Theorem Prover

The paper is about formalization of Set Theory and Elementary Algebra theorems in mathematics and their proofs in a new programming language called LEAN 4 Theorem Prover. The paper describes how such formalization can be done with limited experience in coding and almost no experience in formalization from the first steps to the final project. The paper also describes the available online games for starters such as Natural Number Game, Robo (in German), Set Theory Game, A Lean Intro to Logic. Lean 4 can be used online or through its computer version, by setting up Visual Studio and its Lean 4 extension. The community of Lean users in Zulip (organized team chat app) and some online reference books are also discussed.