A finitely generated commutative monoid is uniquely presented if it has only
a minimal presentation. We give necessary and sufficient conditions for
finitely generated, combinatorially finite, cancellative, commutative monoids
to be uniquely presented. We use the concept of gluing to construct commutative
monoids with this property. Finally for some relevant families of numerical
semigroups we describe the elements that are uniquely presented.Comment: 13 pages, typos corrected, references update