“…We plan to continue this effort not only by trying to find more properties of the Stern-Brocot, Eisenstein-Stern, and Bird trees, but also by investigating whether other areas of mathematics can be made more calculational. We are also building software tools that can help us write calculational proofs in a more reliable way; as an example, we are currently extending the structure editor described in [23] to support automated verification of handwritten calculational proofs. The following lemma is used in the proof of Lemma 2.…”