Lets M be a set and lets T ⊂ Ρ(M) then it is said that T is a topology on M if.

1) ∅, M ∈ T

2) A, B ∈ T => A ∩ B ∈ T

3) Ai ∈ T ∀i =gt; ∪iAi ∈ T.

On the other hand, the topology is the branch of mathematics that deals with issues such as continuity and proximity.