Wigner's theorem revisited

Gyula Maksa; Zsolt Páles

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arXiv · 1211.4600

Wigner's theorem revisited

Gyula Maksa·Zsolt Páles

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Abstract

In this paper, we give the general solution of the functional equation $$\big\{\|f(x)+f(y)\|,\|f(x)-f(y)\|\big\}=\big\{\|x+y\|,\|x-y\|\big\}\qquad(x,y\in X)$$ where $f:X\to Y$ and $X,Y$ are inner product spaces. Related equations are also considered. Our main tool is a real version of Wigner's unitary--antiunitary theorem.

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Gyula Maksa, Zsolt Páles. 2012-11-19. Wigner's theorem revisited. https://arxiv.org/abs/1211.4600

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