Abstract
We give an example of a positive element a in some ordered Banach algebra \(\mathcal A\) such that its spectrum is equal to \(\{1\}\) and it is not greater than or equal to the unit element of \(\mathcal A\).
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The author acknowledges the financial support from the Slovenian Research Agency (Research Core Funding No. P1-0222).
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Drnovšek, R. A note on Huijsmans-de Pagter problem in ordered Banach algebras. Positivity 22, 1355–1357 (2018). https://doi.org/10.1007/s11117-018-0580-7
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DOI: https://doi.org/10.1007/s11117-018-0580-7