English

Birkhoff's Completeness Theorem for Multi-Sorted Algebras Formalized in Agda

Logic in Computer Science 2021-11-16 v1

Abstract

This document provides a formal proof of Birkhoff's completeness theorem for multi-sorted algebras which states that any equational entailment valid in all models is also provable in the equational theory. More precisely, if a certain equation is valid in all models that validate a fixed set of equations, then this equation is derivable from that set using the proof rules for a congruence. The proof has been formalized in Agda version 2.6.2 with the Agda Standard Library version 1.7 and this document reproduces the commented Agda code.

Keywords

Cite

@article{arxiv.2111.07936,
  title  = {Birkhoff's Completeness Theorem for Multi-Sorted Algebras Formalized in Agda},
  author = {Andreas Abel},
  journal= {arXiv preprint arXiv:2111.07936},
  year   = {2021}
}
R2 v1 2026-06-24T07:39:15.029Z