Zobrazeno 1 - 10
of 68
pro vyhledávání: '"Mori, Michiya"'
Autor:
Mori, Michiya, Šemrl, Peter
We study lightlikeness preserving mappings from the $4$-dimensional Minkowski spacetime $\mathcal{M}_4$ to itself under no additional regularity assumptions like continuity, surjectivity, or injectivity. We prove that such a mapping $\phi$ satisfies
Externí odkaz:
http://arxiv.org/abs/2406.18874
Autor:
Izumi, Masaki, Mori, Michiya
In this note, we study the distance from an arbitrary nonzero projection $P$ to the set of nilpotents in a factor $\mathcal{M}$ equipped with a normal faithful tracial state $\tau$. We prove that the distance equals $(2\cos \frac{\tau(P)\pi}{1+2\tau(
Externí odkaz:
http://arxiv.org/abs/2406.09234
Autor:
Mori, Michiya, Oi, Shiho
We study surjective maps between the sets of all self-adjoint elements of unital $C^*$-algebras which satisfy the multiplicatively spectrum-preserving property. We show that such maps are characterized by Jordan isomorphisms and central symmetries. T
Externí odkaz:
http://arxiv.org/abs/2404.04563
Autor:
Mori, Michiya
Problem 155 of the Scottish Book asks whether every bijection $U\colon X\to Y$ between two Banach spaces $X, Y$ with the property that, each point of $X$ has a neighborhood on which $U$ is isometric, is globally isometric on $X$. We prove that this i
Externí odkaz:
http://arxiv.org/abs/2308.03339
Autor:
Mori, Michiya
For a positive integer $n$, we study the collection $\mathcal{F}_{\mathrm{fin}}(n)$ formed of all $n\times n$ matrices whose entries $a_{ij}$, $1\leq i,j\leq n$, can be written as $a_{ij}=\tau(U_j^*U_i)$ for some $n$-tuple $U_1, U_2, \ldots, U_n$ of
Externí odkaz:
http://arxiv.org/abs/2308.03345
Autor:
Mori, Michiya
We prove that the distance from an $n\times n$ complex matrix $M$ to the set of nilpotents is at least $\frac{1}{2}\sec\frac{\pi}{n+2}$ if there is a nonzero projection $P$ such that $PMP=M$ and $M^*M\geq P$. In the particular case where $M$ equals $
Externí odkaz:
http://arxiv.org/abs/2307.04463
Autor:
Mori, Michiya, Šemrl, Peter
Wigner's theorem characterizes isometries of the set of all rank one projections on a Hilbert space. In metric geometry nonexpansive maps and noncontractive maps are well studied generalizations of isometries. We show that under certain conditions Wi
Externí odkaz:
http://arxiv.org/abs/2305.05123
Autor:
Mori, Michiya
We show that every ring isomorphism between the algebras of locally measurable operators for type II$_\infty$ von Neumann algebras is similar to a real $^*$-isomorphism. This together with previous results by the author and Ayupov--Kudaybergenov comp
Externí odkaz:
http://arxiv.org/abs/2206.00875
Autor:
Mori, Michiya
We study (von Neumann) regular $^*$-subalgebras of $B(H)$, which we call R$^*$-algebras. The class of R$^*$-algebras coincides with that of "E$^*$-algebras that are pre-C$^*$-algebras" in the sense of Z. Sz\H{u}cs and B. Tak\'acs. We give examples, p
Externí odkaz:
http://arxiv.org/abs/2107.05806
Autor:
Gehér, György Pál, Mori, Michiya
Let $H$ be a Hilbert space and $P(H)$ be the projective space of all quantum pure states. Wigner's theorem states that every bijection $\phi\colon P(H)\to P(H)$ that preserves the quantum angle between pure states is automatically induced by either a
Externí odkaz:
http://arxiv.org/abs/2102.05780