A commutative doubly-idempotent semiring (cdi-semiring)
is a semilattice
with
and a semilattices
with identity 1 such that
, and
holds for all
. Bounded distributive lattices are cdi-semirings that satisfy
, and the variety of cdi-semirings covers the variety of bounded distributive lattices. Chajda and Länger showed in 2017 that the variety of all cdi-semirings is generated by a 3-element cdi-semiring. We show that there are seven cdi-semirings with a
-semilattice of height less than or equal to 2. We construct all cdi-semirings for which their multiplicative semilattice is a chain with
elements, and we show that up to isomorphism the number of such algebras is the
Catalan number
. We also show that cdi-semirings with a complete atomic Boolean
-semilattice on the set of atoms
A
are determined by singleton-rooted preorder forests on the set
A
. From these results we obtain efficient algorithms to construct all multiplicatively linear cdi-semirings of size n and all Boolean cdi-semirings of size
.