Abstract
We obtain new categorical proofs that generalize the diagonal principles introduced in Castillo and Moreno (Israel J. Math. 140:253–270, 2004) to study the automorphic and partially automorphic character of Banach spaces. We then introduce and study the automorphy index \(\mathfrak a(\cdot)\) for a Banach space, showing that \(\mathfrak a(l_\infty)= \aleph_0\) while \(\mathfrak a(C[0,1])=\aleph_1\).
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This research has been supported in part by project MTM2004-02635.
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Moreno, Y. The Diagonal Functors. Appl Categor Struct 16, 617–627 (2008). https://doi.org/10.1007/s10485-007-9074-7
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DOI: https://doi.org/10.1007/s10485-007-9074-7