symmetric monoidal (∞,1)-category of spectra
A magma is called unital if it has an identity element , hence an element such that for all it satisfies the equation
holds. The identity element is idempotent.
Some authors take a magma to be unital by default (cf. Borceux-Bourn Def. 1.2.1).
There is also a possibly empty version, where the identity element is replaced with a constant function such that for all , and .
The Eckmann-Hilton argument holds for unital magmas: two compatible ones on a set must be equal, associative and commutative.
Examples include unital rings etc.
Last revised on May 25, 2021 at 15:12:10. See the history of this page for a list of all contributions to it.