Unit · year 4
MU-401 · Algebraic Topology
Threads space · structure24 lectures4 theorems
Algebraic invariants that distinguish spaces up to deformation.
Lectures
| L01 | The Programme: Algebra as a Topological Invariant — |
| L02 | Homotopy of Paths and Maps |
| L03 | The Fundamental Group |
| L04 | Basepoints and Change of Basepoint |
| L05 | Functoriality and Homotopy Invariance |
| L06 | The Fundamental Group of the Circle |
| L07 | Covering Spaces — |
| L08 | The Lifting Criterion and Deck Transformations — |
| L09 | The Universal Cover — |
| L10 | Free Groups and Presentations |
| L11 | The Seifert–van Kampen Theorem |
| L12 | Computing π₁ of Surfaces |
| L13 | Retractions and the No-Retraction Theorem |
| L14 | The Brouwer Fixed-Point Theorem |
| L15 | Applications of Brouwer |
| L16 | Simplicial Complexes — |
| L17 | Simplicial Homology — |
| L18 | Singular Homology — |
| L19 | Homotopy Invariance of Homology — |
| L20 | The Mayer–Vietoris Sequence — |
| L21 | The Euler Characteristic |
| L22 | Invariance of the Euler Characteristic |
| L23 | Classification of Surfaces |
| L24 | Synthesis: Holes, Counted Algebraically |
Theorems in this unit
T-118
The fundamental group
Loops up to homotopy form a group invariant of the space.
T-119
The Seifert–van Kampen theorem
The fundamental group of a union from those of its pieces.
T-120
The Brouwer fixed-point theorem
Every continuous self-map of a disc has a fixed point.
T-121
Invariance of the Euler characteristic
V−E+F is a topological invariant.