Compactification Alexandroff extension The Alexandroff extension of a topological space (𝑋,T) is a Compact space (𝑋⋆,T⋆) with an open embedding 𝑐 :𝑋 ↪𝑋⋆ such that 𝑋⋆ ∖𝑐𝑋 ={𝜔}, where 𝜔 is a special point often denoted ∞. #m/def/topology 𝑈∈T⋆⟺{𝑈∈T𝜔∉𝑈𝑋∖𝑈 compact𝜔∈𝑈 Properties Proper map #state/tidy | #lang/en | #SemBr