Work

Bisubdifferentiability of Biconvex Functions

Year: 2025
Type: article
Abstract: In this paper we study biconvex functions. We mainly study three types of biconvex functions: lower semicontinuous biconvex functions, canonical biconvex and bisublinear functions. We also consider biconvex functions that are pointwise upper bounds of some nonempty families of 2-affine, biaffine and bilinear functions, respectively. We show that biconvex functions are closely related to convex functions defined on the tensor product of spaces. The restriction to the space 𝑋 Γ— π‘Œ of convex functions defined on the space 𝑋 βŠ— π‘Œ Γ— (𝑋 Γ— π‘Œ), the restriction to the space 𝑋 Γ— π‘Œ of convex functions defined on the space 𝑋 βŠ— π‘Œis a biconvex function, the restriction to the space 𝑋 Γ— π‘Œ of sublinear functions defined in 𝑋 βŠ— π‘Œis a bisublinear function. In this paper we study bisubdifferentiability of biconvex functions, canonical biconvex and bisublinear functions and study a number of their properties. In this paper we also study properties of biconjugate functions. In this paper we study the bisubdifferential of the maximum function. Using convex hulls of biconvex functions on the tensor product of spaces, criteria for bisubdifferentiability of biconvex functions are obtained. A charac-terization of biconvex and bisublinear functions is considered. In this paper, a number of properties of the bisubdifferential of bisublinear functions are studied and an analogue of HΓΆrmander's theorem for bisublinear functions is obtained. The product of a seminorm is a bisublinear function. Therefore, the bisubdifferentiability properties of bisublinear functions follow from the property of bisubdiffe-rentiability of a product of seminorms.
Language: English
Open Access status: green
OpenAlex ID: W6930495214
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