Summer semester 2024

Discrete Mathematics of Paul Erdős -- NDMI107


  • Course description:
    Paul Erdős (1913 -- 1996) was an outstanding, prolific, influential, legendary mathematician. We will study a selection of his results in number theory, geometry, Ramsey theory, extremal combinatorial problems, and graph theory that laid the foundations of discrete mathematics before it matured into the rich and vibrant discipline of today. From time to time we will stray from his own work to the work of his confrères and disciples, but we shall never escape the gravitational pull of the great man.

    At a leisurely pace, we shall cover a subset of the following topics:
    Proof of Bertrand's postulate. Erdős's proof of Turán's theorem. Hamilton cycles. Ramsey's theorem and Ramsey numbers. Delta-systems and Deza's proof of an Erdős-Lovász conjecture. Sperner's theorem and the Erdős-Ko-Rado theorem. Van der Waerden's theorem and van der Waerden numbers. Extremal graph theory. The Friendship Theorem, strongly regular graphs, and Moore graphs of diameter two. The Erdős-Rényi random graphs and their evolution.

            
The subject and the instructor, ca.1976


Top of this page   •   Sources   •   Bulletin board   •   Record of the material covered in class   •   Erdős links

Sources:

Additional reading:

  • Deza's proof of his theorem
  • Cutting planes in combinatorics
  • Remembering Leo Khachiyan
  • Cutting planes in combinatorics
    Top of this page   •   Sources   •   Bulletin board   •   Record of the material covered in class   •   Erdős links

    Bulletin board


    Top of this page   •   Sources   •   Bulletin board   •   Record of the material covered in class   •   Erdős links

    Record of the material covered in class

    Date             Material covered Homeworks
    Feb 23Chapter 1 up to and including 1.5.2 Homework 1
    Its solution
    Mar 11.5.3-1.5.5, 7.1.1-7.1.3
    Mar 8pages 175-179 up to and including the proof of Theorem 11.5. Homework 2
    Its solution
    Mar 1511.1.1. Statement of Theorem 11.11
    Mar 22Proof of Theorem 11.11 3.1.3.2 up to the upper bound on R(4,4).
    Mar 29Class cancelled
    Apr 5Up to and including page 44
    Apr 12The remainder of Chapter 3. Theorem 4.1 and its proof.
    Apr 19Section 4.2. Section 4.3 up to (and including) display (4.12).
    Apr 26From display (4.12) up to (and excluding) display (4.13).
    May 3The remainder of Chapter 4. Theorem 5.1 and Section 5.1.1.
    May 10Section 5.1.2. Theorem 5.5 and Section 5.2.1.
    May 17Chapter 10 without proofs.
    Jensen's inequality (page 193).
    May 24(Chapter 6)


    Top of this page   •   Sources   •   Bulletin board   •   Record of the material covered in class   •   Erdős links


    Top of this page   •   Sources   •   Bulletin board   •   Record of the material covered in class   •   Erdős links

    Vašek Chvátal's front page at KAM
    Vašek Chvátal's front page at Concordia