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Published online by Cambridge University Press: 02 January 2026
Domains exhibit a variety of different aspects, some are order theoretical, some are topological, some belong to topological algebra. In this paper, we introduce two kinds of congruence relations on domains: I-congruence relation and II-congruence relation on domains. We obtain that there is a bijection from the set of all kernel operators of domain
$P$ preserving directed sups onto the set of all I-congruence relations on
$P$ which exclude
$P\times P$. There is also a bijection from the set of all closure operators of domain
$P$ preserving directed sups onto the set of all II-congruence relations on
$P$ which exclude
$P\times P$. Furthermore, between two domains, we propose a new homomorphism called I-homomorphism and II-homomorphism, respectively. We conclude that the kernels of I-homomorphisms and II-homomorphisms between domains are I-congruence relations and II-congruence relations on domains, respectively. Therefore, we obtain the I-homomorphism and I-isomorphism theorems, as well as II-homomorphism and II-isomorphism theorems for domains. Besides, we give a positive answer to an open problem on homomorphisms and quotients of continuous semilattices posed by G. Gierz, et al.
This work is supported by the National Natural Science Foundation of China (Nos. 12231007, 12501638, 12571498) and by Natural Science Foundation of Henan Province (No. 252300420896).