TY  - JOUR
AU  - M. Breen
TI  - Principal ideals in the semigroup of binary relations  on a finite set: What happens when one element is added to the set.
JO  - Semigroup forum
PY  - 1992
SP  - 129
EP  - 132
VL  - 44
IS  - 1
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/SF_1992__44_1_135137/
ID  - SF_1992__44_1_135137
ER  -