From the 1 of 6 linked papers with an AI index.
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On the Fischer-Muszély equation for the positive cones of -algebras
Daisuke Hirota, Jyamira Oppekepenguin
The paper investigates the Fischer‑Muszély functional equation on the positive semidefinite and positive definite cones of unital C*-algebras, proving that any bijection satisfying…
Surjective isometries on the positive parts of the unit spheres of some function spaces
Yuta Enami, Daisuke Hirota, Hironao Koshimizu +1
We consider the space of continuously differentiable functions on the closed unit interval and the space of Lipschitz continuous fun…
Globalization of local sign structures for phase-isometries on uniform algebras
Yuta Enami, Daisuke Hirota, Izuho Matsuzaki +1
We study surjective phase-isometries between the unit spheres of uniform algebras. Although such maps preserve maximal convex sets up to signs, the resulting local sign ambiguity p…
Norm additive mappings between commutative -algebras in the range
Daisuke Hirota
Let \( A_i \) be a commutative \( C^{*} \)-algebra for \( i = 1, 2 \), and denote by \( A_i^{+} \) its positive cone, consisting of all positive elements of \( A_i \). In this pape…