• 1 Introduction ▶
    • 1.1 Formalization and this document
    • 1.2 Project overview
    • 1.3 Project status
    • 1.4 Notation and terminology
  • 2 Single-sorted presentation ▶
    • 2.1 Single-sorted categories
    • 2.2 Single-sorted functors
    • 2.3 The category of single-sorted categories
  • 3 Single-sorted discretization transformations ▶
    • 3.1 Discrete single-sorted categories
    • 3.2 Discrete single-sorted functors
    • 3.3 Single-sorted discretization functors
  • 4 Single-sorted underlying transformations ▶
    • 4.1 Underlying single-sorted categories
    • 4.2 Underlying single-sorted functors
    • 4.3 Single-sorted underlying functors
  • 5 Many-sorted presentation ▶
    • 5.1 Many-sorted categories
    • 5.2 Many-sorted functors
    • 5.3 The category of many-sorted categories
  • 6 Many-sorted discretization transformations ▶
    • 6.1 Discrete many-sorted categories
    • 6.2 Discrete many-sorted functors
    • 6.3 Many-sorted discretization functors
  • 7 Many-sorted underlying transformations ▶
    • 7.1 Underlying many-sorted categories
    • 7.2 Underlying many-sorted functors
    • 7.3 Many-sorted underlying functors
  • 8 Bibliography
  • Dependency graph

A Formalization of Higher-Order Categories in Lean 4

Enric Cosme Llópez Raúl Ruiz Mora Mario Vago Marzal

2025-2026

  • 1 Introduction
    • 1.1 Formalization and this document
    • 1.2 Project overview
    • 1.3 Project status
    • 1.4 Notation and terminology
  • 2 Single-sorted presentation
    • 2.1 Single-sorted categories
    • 2.2 Single-sorted functors
    • 2.3 The category of single-sorted categories
  • 3 Single-sorted discretization transformations
    • 3.1 Discrete single-sorted categories
    • 3.2 Discrete single-sorted functors
    • 3.3 Single-sorted discretization functors
  • 4 Single-sorted underlying transformations
    • 4.1 Underlying single-sorted categories
    • 4.2 Underlying single-sorted functors
    • 4.3 Single-sorted underlying functors
  • 5 Many-sorted presentation
    • 5.1 Many-sorted categories
    • 5.2 Many-sorted functors
    • 5.3 The category of many-sorted categories
  • 6 Many-sorted discretization transformations
    • 6.1 Discrete many-sorted categories
    • 6.2 Discrete many-sorted functors
    • 6.3 Many-sorted discretization functors
  • 7 Many-sorted underlying transformations
    • 7.1 Underlying many-sorted categories
    • 7.2 Underlying many-sorted functors
    • 7.3 Many-sorted underlying functors
  • 8 Bibliography