Abelian kernels of monoids of order-preserving maps and of some of its extensions

Semigroup Forum vol. 68 (2004), p. 335–356We compute the abelian kernels of some monoids of partial transformations. More precisely, the cases of the symmetric inverse monoid, monoids of order-preserving or order-reversing transformations and monoids of orientationpreserving or orientation-reversing transformations are treated