Published online by Cambridge University Press: 20 November 2018
Let $X$ be a real normed space, $Y$ a Banach space, and $f\,:\,X\,\to \,Y$. We prove theUlam–Hyers stability theorem for the cubic functional equation
in restricted domains. As an application we consider a measure zero stability problem of the inequality
for all $\left( x,\,y \right)$ in $\Gamma \,\subset \,{{\mathbb{R}}^{2}}$ of Lebesgue measure 0.