In this article we describe the formalisation of the Bruhat-Tits tree - an important tool in modern number theory - in the Lean Theorem Prover. Motivated by the goal of connecting to ongoing research, we apply our formalisation to verify a result about harmonic cochains on the tree.

翻译：本文描述了在Lean定理证明器中形式化Bruhat-Tits树——现代数论中的重要工具——的过程。基于连接当前研究的目标，我们应用该形式化验证了关于树上调和上链的一个结果。