##  [Ext Obstruction](/ext-obstruction) 

  ##  [Ext Obstruction](https://algebra.quantumdictionary.io/ext-obstruction-0) 

  

 [![Algebra](/sites/default/files/styles/large/public/2026-01/Algebra.png.webp?itok=3pHxBnUF)](/topic-specific-dictionaries/pure-mathematics/algebra)

- Pure Mathematics -

**Algebra Dictionary**

 







 

 

 

 



 

 

 

 

Definition

An element of an Ext group that encodes the failure of an extension to split or of a lifting problem to have a solution; typically a class in Ext^1 (for non‑split extensions) or in higher Ext groups (for higher order obstructions).