
doi: 10.4064/sm159-2-5
The purpose of this article is to characterize the Fréchet spaces \(F\) which appear as a quotient of the space \(A(\Omega)\) of the complex valued real analytic functions defined on an open subset \(\Omega\) of \(\mathbb R^d\). The paper continues investigations of several authors about the structural theory of the space \(A(\Omega)\). In their important article in [Stud. Math. 142, No. 2, 187--200 (2000; Zbl 0990.46015)], \textit{P. Domanski} and \textit{D. Vogt} showed that every quotient of \(A(\Omega)\) which is a Fréchet space satisfies the restrictive topological invariant \((\overline{\overline{\Omega}})\) of Vogt. This was an important step in the proof that \(A(\Omega)\) has no Schauder basis. At the time when that article was written, the only known infinite-dimensional Fréchet quotient of \(A(\Omega)\) was the countable product of copies of the field of complex numbers. In [Arch. Math. 81, 208--214 (2003; Zbl 1048.46028)], they showed that there is a nuclear Köthe sequence space \(\lambda_ 1(B)\) with a continuous norm which is a quotient of \(A(\Omega)\) for every open set \(\Omega\). The main result of the present article states that a Fréchet space \(F\) is isomorphic to a quotient of \(A(\Omega)\) for some (or any) open subset \(\Omega\) of \(\mathbb R^d\) if and only if it satisfies the property \((\overline{\overline{\Omega}})\) and it is \(n^{1/d}\)-nuclear, or equivalently, if and only if \(E\) has \((\overline{\overline{\Omega}})\) and is isomorphic to a quotient of \(H(D^d)\), the space of holomorphic functions on the \(d\)-dimensional polydisc. An essential step is the characterization of those Fréchet spaces \(F\) such that \(\text{Ext}^1(A(\Omega),F)=0\), a result which is of independent interest.
topological invariants, Locally convex Fréchet spaces and (DF)-spaces, quotient space, space of real-analytic functions, splitting of short exact sequences, Fréchet space, Topological linear spaces of continuous, differentiable or analytic functions, countably normed, Topological invariants ((DN), (\(\Omega\)), etc.) for locally convex spaces, Sequence spaces (including Köthe sequence spaces), \((\text{DN}_\varphi)\)-property
topological invariants, Locally convex Fréchet spaces and (DF)-spaces, quotient space, space of real-analytic functions, splitting of short exact sequences, Fréchet space, Topological linear spaces of continuous, differentiable or analytic functions, countably normed, Topological invariants ((DN), (\(\Omega\)), etc.) for locally convex spaces, Sequence spaces (including Köthe sequence spaces), \((\text{DN}_\varphi)\)-property
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