Let F be a set of filters on X so that if σ,τ∈F , ∀S∈σ , ∀T∈τ , we have S∩T=∅ , then σ∩τ∈F. We say that F is compatible with a topology on X when x∈X is a contact point of A⊂X , if and only if , there is σ∈F such that x∈S and S∩A=∅ for all S∈σ .When is there an F compatible with the topology on X in which finite subsets of X and X are closed ?contact point is also known as adherent point. topologyfiltered algebraabstract algebra