Publications

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2010
Fernandes, Vítor H., M. M. Jesus, V. Maltcev, and J. D. Mitchell. "Endomorphisms of the semigroup of order-preserving mappings." Semigroup Forum. 81 (2010): 277-285.Website
2019
Fernandes, Vítor H., and Paulo G. Santos. "Endomorphisms of semigroups of order-preserving partial transformations." Semigroup Forum (10.1007/s00233-018-9948-z). 99 (2019): 333-344. AbstractWebsite

In this paper we characterize the monoids of endomorphisms of the semigroups PO_n and POI_n of all order-preserving partial transformations and of all order-preserving partial permutations, respectively, of a finite n-chain.

2023
Li, De Biao, and Vítor H. Fernandes. "Endomorphisms of semigroups of oriented transformations." Semigroup Forum (DOI 10.1007/s00233-022-10325-y; Online 2 Dec 2022). 106 (2023): 184-210. AbstractWebsite

In this paper, we characterize the monoid of endomorphisms of the semigroup of all oriented full transformations of a finite chain, as well as the monoid of endomorphisms of the semigroup of all oriented partial transformations and the monoid of endomorphisms of the semigroup of all oriented partial permutations of a finite chain. Characterizations of the monoids of endomorphisms of the subsemigroups of all orientation-preserving transformations of the three semigroups aforementioned are also given. In addition, we compute the number of endomorphisms of each of these six semigroups.

2024
Li, De Biao, and Vítor H. Fernandes. "Endomorphisms of semigroups of monotone transformations." Journal of Algebra and its Applications (DOI 10.1142/S0219498824502244; Online 5 July 2023). 23.13 (2024): 2450224 (17 pages). AbstractWebsite

In this paper, we characterize the monoid of endomorphisms of the semigroup of all monotone full transformations of a finite chain, as well as the monoids of endomorphisms of the semigroup of all monotone partial transformations and of the semigroup of all monotone partial permutations of a finite chain.