In this paper, we introduce two new concepts, namely, a subset being $d_\delta$-connected relative to a topological space, and a subset being $D_\delta$-closed relative to the space. The former is a generalization of the concept of a subset being $\theta$-connected relative to a space, and the latter is analogous to the $H(i)$ space.
"Generalizations of Connected and Compact Sets by $d_\delta$-Closure Operator." Bull. Belg. Math. Soc. Simon Stevin 26 (2) 255 - 273, june 2019. https://doi.org/10.36045/bbms/1561687565