3 papers
math.FA2026
Classical polynomial inequalities for quadratic forms on an octagonal sector
Manwook Han, Sun Kwang Kim, Juan B. Seoane--Sepúlveda
We establish a collection of sharp inequalities for real quadratic forms on the first-quadrant sector of a regular octagon. Starting from the complete extreme-point description of…
math.FA2026
The unit ball of quadratic forms on an octagonal sector
Manwook Han, Sun Kwang Kim, Gustavo A. Muñoz-Fernández +1
Let \[\mathfrak O=\{(x,y)\in[0,1]^2:x+y\le \sqrt2\} \] be the first-quadrant sector of a regular octagon. For quadratic forms \(P(x,y)=ax^2+bxy+cy^2\), we study the supremum norm o…
math.FA2025
Geometry of the space of compact operators endowed with the numerical radius norm
Manwook Han, Sun Kwang Kim
We investigate the space of bounded linear operators on a Banach space equipped with a norm which is equivalent to the operator norm such that the subspace of compact operators is…