18.217 Graph Theory and Additive Combinatorics (Fall 2019, MIT OCW): Lecture 02 - Forbidding a Subgraph I: Mantel's Theorem and Turan's Theorem

18.217 Graph Theory and Additive Combinatorics

18.217 Graph Theory and Additive Combinatorics (Fall 2019, MIT OCW). Instructor: Professor Yufei Zhao. This course examines classical and modern developments in graph theory and additive combinatorics, with a focus on topics and themes that connect the two subjects. The course also introduces students to current research topics and open problems. (from ocw.mit.edu)

Lecture 02 - Forbidding a Subgraph I: Mantel's Theorem and Turan's Theorem

Which triangle-free graph has the maximum number of edges given the number of vertices? Professor Zhao shows the class Mantel's theorem, which says that the answer is a complete bipartite graph. He also discusses generalizations: Turan's theorem (for cliques) and the Erdos-Stone-Simonovits theorem (for general subgraphs).

Go to the Course Home or watch other lectures:

Lecture 01 - A Bridge between Graph Theory and Additive Combinatorics

Lecture 02 - Forbidding a Subgraph I: Mantel's Theorem and Turan's Theorem

Lecture 03 - Forbidding a Subgraph II: Complete Bipartite Subgraph

Lecture 04 - Forbidding a Subgraph III: Algebraic Constructions

Lecture 05 - Forbidding a Subgraph IV: Dependent Random Choice

Lecture 06 - Szemeredi's Graph Regularity Lemma I: Statement and Proof

Lecture 07 - Szemeredi's Graph Regularity Lemma II: Triangle Removal Lemma

Lecture 08 - Szemeredi's Graph Regularity Lemma III: Further Applications

Lecture 09 - Szemeredi's Graph Regularity Lemma IV: Induced Removal Lemma

Lecture 10 - Szemeredi's Graph Regularity Lemma V: Hypergraph Removal and Spectral Proof

Lecture 11 - Pseudo-random Graph I: Quasirandomness