The strong spectral extension property does not imply the multiplicative Hahn–Banach property
Studia Mathematica 153 (2002), 297-301 MSC: Primary 46J05; Secondary 46J20, 46J30, 46A22. DOI: 10.4064/sm153-3-6
An example is given of a semisimple commutative Banach algebra that has the strong spectral extension property but fails the multiplicative Hahn–Banach property. This answers a question posed by M. J. Meyer in .