1 Introduction

2 Preliminaries

3 δ-invariants

4 Inequalities involving δ-invariants and ideal submanifolds

5 Ideal CR submanifolds in complex hyperbolic space

6 Ideal CR submanifolds in complex projective space

7 Ideal CR submanifolds in the nearly Kähler 6-sphere

8 Ideal contact CR submanifolds in odd-dimensional unit spheres

9 Related topics