quandle

== English == === Etymology === Coined by David Joyce in his 1982 paper A classifying invariant of knots: the knot quandle. === Noun === quandle (plural quandles) (mathematics) A rack, Q {\displaystyle \scriptstyle \mathrm {Q} \,} , such that ∀ a ∈ Q {\displaystyle \scriptstyle \forall a\;\in \;\mathrm {Q} } a ▹ a = a {\displaystyle a\triangleright a=a} or equivalently a ◃ a = a {\displaystyle a\triangleleft a=a} . ==== Derived terms ==== ==== Translations ====