Arens square

In mathematics, the Arens square is a topological space.
Definition.
Arens square is the topological space formula_1 where
The topology formula_3 is defined from the following basis. Every point of formula_4 is given the local basis of relatively open sets inherited from the Euclidean topology on formula_5. The remaining points of formula_6 are given the local bases
Properties.
The space formula_1 satisfies that: