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On Turán-type problems and the abstract chromatic number

Dániel Gerbner, Hilal Hama Karim, Gaurav Kucheriya

Abstract

In 2020, Coregliano and Razborov introduced a general framework to study limits of combinatorial objects, using logic and model theory. They introduced the abstract chromatic number and proved/reproved multiple Erdős-Stone-Simonovits-type theorems in different settings. In 2022, Coregliano extended this by showing that similar results hold when we count copies of $K_t$ instead of edges. Our aim is threefold. First, we provide a purely combinatorial approach. Second, we extend their results by showing several other graph parameters and other settings where Erdős-Stone-Simonovits-type theorems follow. Third, we go beyond determining asymptotics and obtain corresponding stability, supersaturation, and sometimes even exact results.

On Turán-type problems and the abstract chromatic number

Abstract

In 2020, Coregliano and Razborov introduced a general framework to study limits of combinatorial objects, using logic and model theory. They introduced the abstract chromatic number and proved/reproved multiple Erdős-Stone-Simonovits-type theorems in different settings. In 2022, Coregliano extended this by showing that similar results hold when we count copies of instead of edges. Our aim is threefold. First, we provide a purely combinatorial approach. Second, we extend their results by showing several other graph parameters and other settings where Erdős-Stone-Simonovits-type theorems follow. Third, we go beyond determining asymptotics and obtain corresponding stability, supersaturation, and sometimes even exact results.

Paper Structure

This paper contains 5 sections, 9 theorems, 2 equations.

Key Result

Lemma 1.2

Hereditary partitions are suitable.

Theorems & Definitions (27)

  • Definition 1.1
  • Lemma 1.2
  • proof
  • Definition 1.3
  • Definition 1.4
  • Theorem 1.1
  • proof
  • Theorem 2.1
  • proof
  • Theorem 2.2
  • ...and 17 more