Abstract In this paper, we establish a connection between categorical closedness and nontopologizability of semigroups. particular, for the class

In concurrency theory, there are several examples where the interleaved model of concurrency can distinguish between execution sequences which are not significantly different. One such example is sequences that differ from each other by stuttering, i. e., the number of times a state can adjacently repeat. Another example is executions that differ only by the ordering of independently executed e...

Obtaining a weaker condition that preserves some inspired topological properties is always desirable. As result, we introduce the concept of infra-fuzzy topology, which subset family degrades fuzzy topology by omitting closedness under arbitrary unions. Fundamental spaces are investigated, including open and closed sets, interior closure operators, boundary set. It not possible to expect latter...

In the present paper, we consider a 2 ? block operator matrices with unbounded entry operators acting on Banach spaces. Under some conditions, develop criteria for its self-adjointness and closedness. The obtained results are applied to an Hamiltonian matrix.