English

The chain rule for $\mathcal F$-differentiation

Functional Analysis 2024-03-28 v2

Abstract

Let XX be a perfect, compact subset of the complex plane, and let D(1)(X)D^{(1)}(X) denote the (complex) algebra of continuously complex-differentiable functions on XX. Then D(1)(X)D^{(1)}(X) is a normed algebra of functions but, in some cases, fails to be a Banach function algebra. Bland and the second author investigated the completion of the algebra D(1)(X)D^{(1)}(X), for certain sets XX and collections F\mathcal{F} of paths in XX, by considering F\mathcal{F}-differentiable functions on XX. In this paper, we investigate composition, the chain rule, and the quotient rule for this notion of differentiability. We give an example where the chain rule fails, and give a number of sufficient conditions for the chain rule to hold. Where the chain rule holds, we observe that the Fa\'a di Bruno formula for higher derivatives is valid, and this allows us to give some results on homomorphisms between certain algebras of F\mathcal{F}-differentiable functions.

Keywords

Cite

@article{arxiv.1511.09276,
  title  = {The chain rule for $\mathcal F$-differentiation},
  author = {T. Chaobankoh and J. F. Feinstein and S. Morley},
  journal= {arXiv preprint arXiv:1511.09276},
  year   = {2024}
}

Comments

12 pages, submitted

R2 v1 2026-06-22T11:57:20.792Z