Algorithm

The following algorithm determines <D>, the submonoid of a given monoid M generated by a given subset D.
We shall use the notation xN for {xn | n  N}.

• Input: a finite monoid (e.g., multiplication table of) M and a subset D.
• Output: <D>.

1. S := {e}.
2. N := D.
3. While N is not empty   do
                        S := S N;         N := (_xD xN)\S
4. Return S.