Equality of the union and indexed annihilator families

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Let VV be a Banach algebra, and let XX be a Banach space. Let φ ⁣:V→X\varphi\!:V\to X be a bounded linear map. For z∈Vz\in V, write C−1(z){\mathfrak{C}}_{-1}(z) for the set of corresponding good-path coefficients, and let S∪φ(z){\mathfrak{S}}_\cup^\varphi(z) and Scφ(z){\mathfrak{S}}_c^\varphi(z) denote the associated families. Equality conjecture. For all z∈Vz\in V,

S∪φ(z)=⋃c∈C−1(z)Scφ(z).{\mathfrak{S}}_\cup^\varphi(z)=\bigcup_{c\in{\mathfrak{C}}_{-1}(z)}{\mathfrak{S}}_c^\varphi(z).

The preceding corollary establishes the inclusion from right to left; the conjecture asserts that every element of S∪φ(z){\mathfrak{S}}_\cup^\varphi(z) arises from one coefficient c∈C−1(z)c\in{\mathfrak{C}}_{-1}(z).

References

Primary source

Daniel Falkowski and Carl-Fredrik Lidgren, “Conjugating by singular operators: On the boundedness of similarity transforms near singular points”, arXiv:2410.19161 (2024).

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