In 1906, he introduced the concept of abstract space, including metric space, topological space and vector space and was also one of the founders of functional analysis.
He was one of the founders of functional analysis. In 1906, he introduced the concept of abstract space, including metric space, topological space and vector space.
In 1906, he introduced the concept of abstract space, including metric space, topological space and vector space. He was one of the founders of functional analysis.
In 1906, he introduced the concept of abstract space, including metric space, topological space and vector space. He was one of the founders of functional analysis.