👉 Itō's lemma is a fundamental result in functional analysis. It is named after Masayoshi Ito, a Japanese mathematician who introduced it to the mathematical community and was later awarded the Fields Medal for his work on it. The theorem states that if $u$ and $v$ are two continuous functions defined on a closed interval [a, b] with values in a Banach space, then there exists an element $\xi \in (a, b)$ such that $u(x
