Unital Magma

A magma with an identity element
Unital Magma

A unital magma is a (M,)(M, \cdot) equipped with an identity element eMe \in M satisfying

ea=ae=ae \cdot a = a \cdot e = a

for all aMa \in M.

This is the weakest structure requiring an identity. All , , and are unital magmas.

Examples:

  • Any monoid, loop, or group
  • A set with a non-associative operation that still has an identity element