Definition. Scott open [math-7H66]

Named after Dana S. Scott.

Let DD be a cpo. A subset UU of DD is said to be Scott open if

  1. whenever x∈Ux \in U and x⊑yx \sqsubseteq y then y∈Uy \in U; and
  2. whenever M⊆DM \subseteq D is directed and ⨆M∈U\bigsqcup M \in U, then M∩U≠∅M \cap U \ne \varnothing.

Definition Scott topology and continuous [math-8KRP]

Scott open subsets of DD form a topology, this is the Scott topology on DD. A continuous function f:D→Ef : D \to E will preserve directed least element f(⊔DX)=⊔Ef(X)f(\sqcup_D X) = \sqcup_E f(X) for all directed X⊆DX \subseteq D.