Minkowski product of convex sets and product numerical range
نویسندگان
چکیده
منابع مشابه
Minkowski product of convex sets and product numerical range
Let K1,K2 be two compact convex sets in C. Their Minkowski product is the set K1K2 = {ab : a ∈ K1, b ∈ K2}. We show that the set K1K2 is star-shaped if K1 is a line segment or a circular disk. Examples for K1 and K2 are given so that K1 and K2 are triangles (including interior) and K1K2 is not star-shaped. This gives a negative answer to a conjecture by Puchala et. al concerning the product num...
متن کاملProduct of Operators and Numerical Range
We show that a bounded linear operator A ∈ B(H) is a multiple of a unitary operator if and only if AZ and ZA always have the same numerical radius or the same numerical range for all (rank one) Z ∈ B(H). More generally, for any bounded linear operators A,B ∈ B(H), we show that AZ and ZB always have the same numerical radius (resp., the same numerical range) for all (rank one) Z ∈ B(H) if and on...
متن کاملOn Volume Product Inequalities for Convex Sets
The volume of the polar body of a symmetric convex set K of Rd is investigated. It is shown that its reciprocal is a convex function of the time t along movements, in which every point of K moves with constant speed parallel to a fixed direction. This result is applied to find reverse forms of the Lp-Blaschke-Santaló inequality for two-dimensional convex sets.
متن کاملNumerical Range of Lie Product of Operators
Denote by W (A) the numerical range of a bounded linear operator A, and [A, B] = AB −BA the Lie product of two operators A and B. Let H, K be complex Hilbert spaces of dimension ≥ 2 and Φ : B(H) → B(K) be a map whose range contains all operators of rank ≤ 1. It is shown that Φ satisfies that W ([Φ(A), Φ(B)]) = W ([A, B]) for any A, B ∈ B(H) if and only if dim H = dim K, there exist ε ∈ {1,−1}, ...
متن کاملIntervals and Convex Sets in Strong Product of Graphs
In this note we consider intervals and convex sets of strong product. Vertices of an arbitrary interval of G H are classified with shortest path properties of one factor and a walk properties of a slightly modified second factor. The convex sets of the strong product are characterized by convexity of projections to both factors and three other local properties, one of them being 2-convexity.
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Operators and Matrices
سال: 2016
ISSN: 1846-3886
DOI: 10.7153/oam-10-53