Type Theory and Univalent Mathematics

Introduction

A very informal view of Type Theory

Martin-Löf Type Theory

A minimal Type Theory in Martin-Löf style

2-categorical constructions

Basic 2-categorical constructions

Negation

Negation, decidability, and related propositions

Natural Numbers

definition and properties of the natural numbers

Pointed Types and Loop Spaces

Pointed Types, Loop Spaces, and the Eckmann-Hilton argument

Basic Homotopy

Basic homotopy theory constructions: weak equivalences, homotopy equivalences, homotopy fibers, and type-theoretic constructions inspired by them

Propositions, Sets and Logic

Singletons, Propositions, and Sets. Excluded Middle

Univalence—Ⅰ

Towards the univalence axiom, function extensionality

Function Extensionality

Proof of the equivalence of the various function extensionality axioms

Univalence—Ⅱ

Univalence implies function extensionality

Univalence—Ⅲ

Global univalence and functional extensionality

Propositions, Sets and Logic—Ⅱ

More about Propositions from a univalent point of view

Univalence—Ⅳ

Some corollaries of the univalence and function extensionality axioms

Magmas, Monoids, Groups

First examples of algebraic structures


Leitfaden

Chapter and Module dependency graph


Simple Agda experiments

Natural numbers

A simple example where we code the naturals and few other elementary constructions

Propositional Equality

Definition of propositional equality and some simple theorems using it

Associativity of addition

Some additional simple theorems and techniques. We prove that the addition of naturals is associative