Harder–Narasimhan stratification

The Harder–Narasimhan (HN) stratification is a concept in the field of algebraic geometry, particularly in the study of moduli spaces of vector bundles over algebraic curves or more generally over varieties. It is named after mathematicians J. Harder and M. Narasimhan, who introduced this idea in the context of vector bundles. The HN stratification provides a way to organize objects (such as vector bundles) based on their stability properties.