In Chapter 1, we investigate the cancellation monoids.
第一章，主要研究消去幺半群。
2
Furthermore, the meet and the join for the good congruence lattice are determined for the semilattice of commutative cancellative monoids.
特别是确定了交换的可消幺半群的半格的好同余格上的交与并运算。
3
Bipartite graphs with P-regular endomorphism monoids are characterized. P-regularity of the endomorphism monoid of lexicographic product of graphs is discussed.