Compare with Monoid

A Monoid is a triplet \((E,∙,e)\) s.t.

• \(E\) a set
• \(∙:E×E→E\)
• \(e:1→E\)

Satisfying

• \(x∙(y∙z) = (x∙y)∙z, ∀x,y,z∈E\)
• \(e∙x = x = x∙e, ∀x∈E\)