Finite monogenerated groupoids
G satisfying the left distributive law
x · (
y ·
z) = (
x ·
y) · (
x ·
z) are studied. They are shown to reduce over
qG = {(
a,
b)
G2;
ca =
cb for all
c G} and
pG = {(
a,
b)
G2;
ac =
bc for all
c G} to a groupoid isomorphic to
Ak =
Ak(*),
k ≥ 0. (
Ak is the unique left distributive groupoid on {1,…,2
k} with
a * 1 ≡
a + 1 mod 2
k for every 1 ≤
a ≤ 2
k.)
G Ak is proved to hold whenever
b a ·
b equals id
G for some
a G. We describe all cases when
G =
Ga {
b} for some
a,
b G, and all cases when there exists a binary operation
on
G such that
G(·,
) satisfies the axioms of left distributive algebras.