REFERENCES
- Bulman-Fleming , S. , Gilmour , A. ( 2009 ). Flatness properties of diagonal acts over monoids . Semigroup Forum 79 ( 2 ): 298 – 314 .
- Bulman-Fleming , S. , McDowell , K. ( 1990 ). Coherent monoids . In: et al. , eds. Lattices, Semigroups and Universal Algebra . New York : Plenum Press , pp. 29 – 37 .
- Ershad , M. , Sedaghatjoo , M. ( 2011 ). On a conjecture of Bulman-Fleming and Gilmour . Semigroup Forum 82 : 542 – 546 .
- Fountain , J. ( 1977 ). Right PP monoids with central idempotents . Semigroup Forum 13 : 229 – 237 .
- Gallagher , P. , Ruškuc , N. ( 2005 ). Generation of diagonal acts of some semigroups of transformations and relations . Bull. Austral. Math. Soc. 72 : 139 – 146 .
- Kilp , M. ( 1973 ). Commutative monoids all of whose principal ideals are projective . Semigroup Forum 6 : 334 – 339 .
- Kilp , M. , Knauer , U. , Mikhalev , A. ( 2000 ). Monoids, Acts and Categories . Berlin : W. de Gruyter .
- Kozhukhov , I. B. ( 1981 ). Left chain semigroups . Semigroup Forum 22 : 1 – 8 .
- Laan , V. ( 2001 ). Pullbacks and flatness properties of acts. I . Communications in Algebra 29 ( 2 ): 829 – 850 .
- Liu , Z. K. , Yang , Y. B. ( 1994 ). Monoids over which every flat right act satisfies condition (P) . Communications in Algebra 22 ( 8 ): 2861 – 2875 .
- Sedaghatjoo , M. , Khosravi , M. , Ershad , M. ( 2009 ). Principally weakly and weakly coherent monoids . Communications in Algebra 37 ( 12 ): 4281 – 4295 .
- Communicated by V. Gould.