reducible

Definition

• A non-empty closed subset C of X is said reducible if there are non-empty, proper closed subsets C_1,C_2 of C, such that C = C_1 ∪ C_2.

Reference

• M.L. Colasante and D. Van der Zypen, Minimal R_1, minimal regular and minimal presober topologies, Revista Notas de Matemática, Vol.5(1),No. 275, 2009, pp.73-84