Incidence Geometry and Its Applications (Summer students programme, 2018)

Instructor Arijit Ghosh

Description A brief introduction to Incidence Geometry.

Intended Audience TCS summer students at IMSC.

References

  • [KMS12] Kaplan, Matousek and Sharir, Simple Proofs of Classical Theorems in Discrete Geometry via the Guth--Katz Polynomial Partitioning Technique, Discrete & Computational Geometry, 48 (3): 499–517, 2012.

  • [D12] Z. Dvir, Incidence Theorems and Their Applications, Foundations and Trends in Theoretical Computer Science, 2012.

  • [LR] Landau-Ramanujan Constant.

  • [I08] A. Iosevich, Fourier Analysis and Geometric Combinatorics, Topics in Mathematical Analysis, pages 321-335, 2008.

Lecture details

Topics covered in Lecture 1

  • Statements of Szemeredi-Trotter (ST) theorem and Pach-Sharir's refinement of ST Theorem.

  • Applications of ST:

      • Bounding the number of heavy lines.

      • Beck's Ramsey-type result for points and lines in 2D.

      • Elekes's Sum-Product estimate using ST.

      • Erdos's Unit Distance estimate using ST.

  • Lower bound on Erdos's distinct distance problem using Landau-Ramanujan Constant [LR].

  • Reading materials:

      • Sections 2.1 and 2.2 from Chapter 2 of [D12].

      • Read [LR].

Topics covered in Lecture 2

  • Number of lattice points on a Convex Curve in 2D via ST theorem.

  • Statement of Guth-Katz's Polynomial Partitioning Theorem.

  • Existence of low degree of polynomials vanishing on a finite set in d-dimensional Euclidean space.

  • Statement of Ham-Sandwich Theorem.

  • Statement and Proof of Polynomial Ham-Sandwich Theorem.

  • Simple properties of polynomials.

  • Reading materials:

      • Sections 2.5 from Chapter 2 of [D12].

      • Sections 1 and 2 from [KMS12].

Topics covered in Lecture 3

  • Proof of ST Theorem using Polynomial Partitioning Theorem.

  • Proof of Polynomial Partitioning Theorem using Polynomial Ham-Sandwich Theorem.

  • Reading materials:

      • Section 4 of [I08].

      • Sections 2.5 from Chapter 2 of [D12].

      • Sections 1 and 2 from [KMS12].

Topics covered in Lecture 4

  • Basic properties of planar graphs.

  • Proof of Crossing Lemma via the probabilistic method.

  • Proof of ST Theorem via Crossing Lemma.

  • Reading materials:

      • Sections 2.5 from Chapter 2 of [D12].

      • Sections 1 and 2 from [KMS12].