For extension of morphisms in the sense dual to lift see at extension.
symmetric monoidal (∞,1)-category of spectra
Given any kind of object $A$ in algebra, such as an associative algebra or a group or a Lie algebra, etc., then an extension of $A$ is an epimorphism
Typically the kernel of an epimorphism will exist in the given category, leading to a short exact sequence
Then one says that $\widehat A$ is an extension by $ker(p)$ of $A$.
Created on July 31, 2018 at 10:06:49. See the history of this page for a list of all contributions to it.