Displaying 21 – 40 of 57

Showing per page

Isometric classification of Sobolev spaces on graphs

M. I. Ostrovskii (2007)

Colloquium Mathematicae

Isometric Sobolev spaces on finite graphs are characterized. The characterization implies that the following analogue of the Banach-Stone theorem is valid: if two Sobolev spaces on 3-connected graphs, with the exponent which is not an even integer, are isometric, then the corresponding graphs are isomorphic. As a corollary it is shown that for each finite group and each p which is not an even integer, there exists n ∈ ℕ and a subspace L p whose group of isometries is the direct product × ℤ₂.

Monotonicity of the maximum of inner product norms

Boris Lavrič (2004)

Commentationes Mathematicae Universitatis Carolinae

Let 𝕂 be the field of real or complex numbers. In this note we characterize all inner product norms p 1 , ... , p m on 𝕂 n for which the norm x max { p 1 ( x ) , ... , p m ( x ) } on 𝕂 n is monotonic.

On area and side lengths of triangles in normed planes

Gennadiy Averkov, Horst Martini (2009)

Colloquium Mathematicae

Let d be a d-dimensional normed space with norm ||·|| and let B be the unit ball in d . Let us fix a Lebesgue measure V B in d with V B ( B ) = 1 . This measure will play the role of the volume in d . We consider an arbitrary simplex T in d with prescribed edge lengths. For the case d = 2, sharp upper and lower bounds of V B ( T ) are determined. For d ≥ 3 it is noticed that the tight lower bound of V B ( T ) is zero.

Currently displaying 21 – 40 of 57