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Corrigendum: Analytic representation theory of Lie groups: general theory and analytic globalizations of Harish-Chandra modules

Part of: Lie groups

Published online by Cambridge University Press:  19 January 2017

Heiko Gimperlein
Affiliation:
Maxwell Institute for Mathematical Sciences and Department of Mathematics, Heriot-Watt University, Edinburgh, EH14 4AS, UK Institut für Mathematik, Universität Paderborn, Warburger Str. 100, 33098 Paderborn, Germany email [email protected]
Bernhard Krötz
Affiliation:
Institut für Mathematik, Universität Paderborn, Warburger Str. 100, 33098 Paderborn, Germany email [email protected]
Henrik Schlichtkrull
Affiliation:
Department of Mathematics, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark email [email protected]
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Abstract

We correct the proof of the main result of the paper, Theorem 5.7. Our corrected proof relies on weaker versions of a number of intermediate results from the paper. The original, more general, versions of these statements are not known to be true.

Type
Corrigendum
Copyright
© The Authors 2017 

For a representation $\unicode[STIX]{x1D70B}$ of a connected Lie group $G$ on a topological vector space $E$ we defined in [Reference Gimperlein, Krötz and SchlichtkrullGKS11] a vector subspace $E^{\unicode[STIX]{x1D714}}$ of $E$ of analytic vectors. Further, we equipped $E^{\unicode[STIX]{x1D714}}$ with an inductive limit topology. We called a representation $(\unicode[STIX]{x1D70B},E)$ analytic if $E=E^{\unicode[STIX]{x1D714}}$ as topological vector spaces.

Some mistakes in the paper have been pointed out by Glöckner (see [Reference GlöcknerGlö13]). For a representation $(\unicode[STIX]{x1D70B},E)$ and a closed $G$ -invariant subspace $F$ of $E$ we asserted in Lemma 3.6(i) that $F^{\unicode[STIX]{x1D714}}=E^{\unicode[STIX]{x1D714}}\cap F$ as a topological space. Based on that, we further asserted in Lemma 3.6(ii) that the inclusion $E^{\unicode[STIX]{x1D714}}/F^{\unicode[STIX]{x1D714}}\rightarrow (E/F)^{\unicode[STIX]{x1D714}}$ is continuous and in Lemma 3.11 that if $(\unicode[STIX]{x1D70B},E)$ is analytic then so is the restriction to $F$ . However, there is a gap in the proof of the first assertion, and presently it is not clear to us whether the above statements are then true in this generality (for unitary representations $(\unicode[STIX]{x1D70B},E)$ they are straightforward). Our proof does give the following weaker version of the two lemmas.

Lemma 1. Let $(\unicode[STIX]{x1D70B},E)$ be a representation and let $F\subset E$ be a closed invariant subspace. Then:

  1. (i) $F^{\unicode[STIX]{x1D714}}=E^{\unicode[STIX]{x1D714}}\cap F$ as vector spaces and with continuous inclusion $F^{\unicode[STIX]{x1D714}}\rightarrow E^{\unicode[STIX]{x1D714}}$ ;

  2. (ii) $E^{\unicode[STIX]{x1D714}}/E^{\unicode[STIX]{x1D714}}\cap F\subset (E/F)^{\unicode[STIX]{x1D714}}$ continuously;

  3. (iii) if $(\unicode[STIX]{x1D70B},E)$ is an analytic representation, then $\unicode[STIX]{x1D70B}$ induces an analytic representation on $E/F$ .

Indeed, for (iii) note that if $E$ is analytic, $E/F=E^{\unicode[STIX]{x1D714}}/E^{\unicode[STIX]{x1D714}}\cap F\subset (E/F)^{\unicode[STIX]{x1D714}}$ continuously by (ii), and $(E/F)^{\unicode[STIX]{x1D714}}\subset E/F$ continuously.

Further, we asserted in Proposition 3.7 a general completeness property of the functor which associates $E^{\unicode[STIX]{x1D714}}$ to $E$ . However, there is a gap in the proof, which asserts that $v_{i}\rightarrow v$ in the topology of $E^{\unicode[STIX]{x1D714}}$ . As statements in this generality are not needed for the main result, we can leave out the proposition (together with Remark 3.8).

Attached to $G$ we introduced a certain analytic convolution algebra ${\mathcal{A}}(G)$ . A central theme of the paper is the relation of analytic representations of $G$ to algebra representations of ${\mathcal{A}}(G)$ on $E$ : ${\mathcal{A}}(G)\times E\rightarrow E$ . In Proposition 4.2(ii), we claimed that the bilinear map ${\mathcal{A}}(G)\times {\mathcal{A}}(G)\rightarrow {\mathcal{A}}(G)$ is continuous. However, the proof shows only separate continuity. For a similar reason, we need to weaken Proposition 4.6 to the following.

Proposition 2. Let $(\unicode[STIX]{x1D70B},E)$ be an $F$ -representation. The assignment

$$\begin{eqnarray}(f,v)\mapsto \unicode[STIX]{x1D6F1}(f)v:=\int _{G}f(g)\unicode[STIX]{x1D70B}(g)v\,dg\end{eqnarray}$$

defines a continuous bilinear map

$$\begin{eqnarray}{\mathcal{A}}_{n}(G)\times E\rightarrow E_{n}\end{eqnarray}$$

for every $n\in \mathbb{N}$ , and a separately continuous map

$$\begin{eqnarray}{\mathcal{A}}(G)\times E\rightarrow E^{\unicode[STIX]{x1D714}}\end{eqnarray}$$

(with convergence of the defining integral in $E^{\unicode[STIX]{x1D714}}$ ). Moreover, if $(\unicode[STIX]{x1D70B},E)$ is a Banach representation, then the latter bilinear map is continuous.

Proof. The first statement is proved in the article, and thus only the statement for $\unicode[STIX]{x1D70B}$ a Banach representation remains to be proved. We repeat the first part of the proof, now with $p$ denoting the fixed norm of $E$ . The constants $c,C$ such that

$$\begin{eqnarray}p(\unicode[STIX]{x1D70B}(g)v)\leqslant Ce^{cd(g)}p(v)\quad (g\in G,v\in E)\end{eqnarray}$$

and $N,C_{1}$ such that

$$\begin{eqnarray}C_{1}:=\int _{G}e^{(c-N)d(g)}\,dg<\infty\end{eqnarray}$$

are then all fixed, and so is $\unicode[STIX]{x1D716}=1/(CC_{1})$ .

Let $n\in \mathbb{N}$ and an open $0$ -neighborhood $W_{n}\subset E_{n}$ be given. We may assume that

$$\begin{eqnarray}W_{n}=\{v\in E_{n}\mid p(\unicode[STIX]{x1D70B}(K_{n})v)<\unicode[STIX]{x1D716}_{n}\}\end{eqnarray}$$

with $K_{n}\subset GV_{n}$ compact and $\unicode[STIX]{x1D716}_{n}>0$ . Let

$$\begin{eqnarray}O_{n}:=\Bigl\{f\in {\mathcal{O}}(V_{n}G)|\sup _{z\in K_{n},g\in G}|f(z^{-1}g)|e^{Nd(g)}<\unicode[STIX]{x1D716}\unicode[STIX]{x1D716}_{n}\Bigr\}\subset {\mathcal{A}}_{n}(G).\end{eqnarray}$$

The computation in the given proof shows that if $f\in O_{n}$ and $p(v)<1$ , then $\unicode[STIX]{x1D6F1}(f)v\in W_{n}$ . The asserted bi-continuity of ${\mathcal{A}}(G)\times E\rightarrow E^{\unicode[STIX]{x1D714}}$ follows.◻

As a consequence, we obtain as in Example 4.10(a), but only for Banach representations $(\unicode[STIX]{x1D70B},E)$ , that $E^{\unicode[STIX]{x1D714}}$ is ${\mathcal{A}}(G)$ -tempered. In particular, ${\mathcal{A}}(G)$ need not itself be ${\mathcal{A}}(G)$ -tempered, and we need to replace Lemma 5.1(i) by the following weaker version.

Lemma 3. $V^{\text{min}}$ is an analytic globalization of $V$ and it carries an algebra action

$$\begin{eqnarray}(f,v)\mapsto \unicode[STIX]{x1D6F1}(f)v,\quad {\mathcal{A}}(G)\times V^{\text{min}}\rightarrow V^{\text{min}}\end{eqnarray}$$

of ${\mathcal{A}}(G)$ , which is separately continuous.

The main result of the paper, Theorem 5.7, has two statements concerning a Harish-Chandra module $V$ with a globalization $E$ :

  1. (1) if $E$ is analytic ${\mathcal{A}}(G)$ -tempered, then $E=V^{\text{min}}$ ;

  2. (2) if $E$ is an $F$ -globalization, then $E^{\unicode[STIX]{x1D714}}=V^{\text{min}}$ .

The proof, which relied on Lemma 3.11 and Proposition 4.6, respectively, needs to be corrected. The proof of (1) if $V$ is irreducible needs no modification. For the general case it can be adjusted as follows.

Like in the paper, it suffices to consider an exact sequence of Harish-Chandra modules $0\rightarrow V_{1}\rightarrow V\rightarrow V_{2}\rightarrow 0$ , where both $V_{1}$ and $V_{2}$ have unique analytic ${\mathcal{A}}(G)$ -tempered globalizations. We show that the same holds for $V$ .

Let $E_{1}$ be the closure of $V_{1}$ in $E$ and $E_{2}=E/E_{1}$ . By Lemma 1(iii), $E_{2}$ is an analytic ${\mathcal{A}}(G)$ -tempered globalization of $V_{2}$ , so that by assumption $E_{2}=V_{2}^{\text{min}}={\mathcal{A}}(G)V_{2}$ as topological vector spaces.

In a first step we prove that $E_{1}=V_{1}^{\text{min}}={\mathcal{A}}(G)V_{1}$ as vector spaces. For that, we note first that $E_{1}$ is ${\mathcal{A}}(G)$ -tempered and that $V_{1}^{\text{min}}\subset E_{1}$ continuously. Next, by Proposition 5.3 (which holds for any ${\mathcal{A}}(G)$ -tempered representation), we may embed $E_{1}\subset F_{1}$ continuously into a Banach globalization of $F_{1}$ of $V_{1}$ . Moreover, the proof shows that the embedding is compatible with the action by ${\mathcal{A}}(G)$ . It follows that $E_{1}^{\unicode[STIX]{x1D714}}\subset F_{1}^{\unicode[STIX]{x1D714}}$ continuously and as ${\mathcal{A}}(G)$ -modules. Further, note that since $E$ is analytic, from Lemma 1(i), we also obtain $E_{1}^{\unicode[STIX]{x1D714}}=E^{\unicode[STIX]{x1D714}}\cap E_{1}=E_{1}$ as vector spaces. Hence, $V_{1}^{\text{min}}\subset E_{1}\subset F_{1}^{\unicode[STIX]{x1D714}}$ . By assumption, $V_{1}$ has a unique ${\mathcal{A}}(G)$ -tempered globalization and hence $F_{1}^{\unicode[STIX]{x1D714}}\simeq V_{1}^{\text{min}}$ . Therefore, $V_{1}^{\text{min}}\subset E_{1}\subset F_{1}^{\unicode[STIX]{x1D714}}\simeq V_{1}^{\text{min}}$ . As these maps respect the structure as ${\mathcal{A}}(G)$ -modules, the inclusion is also surjective: $V_{1}^{\text{min}}=E_{1}$ .

Being an inductive limit, $E_{1}=F_{1}^{\unicode[STIX]{x1D714}}$ is an ultrabornological space, and $V_{1}^{\text{min}}$ is webbed (see the reference in the proof of Proposition 4.6). We conclude from the open mapping theorem that $V_{1}^{\text{min}}=E_{1}$ also as topological vector spaces.

With Lemma 5.2, we now have a diagram of topological vector spaces

where the vertical arrow in the middle signifies the continuous inclusion $V^{\text{min}}={\mathcal{A}}(G)V\subset E$ , and where the rows are exact. The five lemma implies $V^{\text{min}}=E$ as a vector space, and as in the article we conclude from [DS79] that this is then a topological identity.

Finally, for (2) we recall from Corollary 3.5 that $(E^{\infty })^{\unicode[STIX]{x1D714}}=E^{\unicode[STIX]{x1D714}}$ . The Casselman–Wallach smooth globalization theorem asserts the existence of a Banach globalization $F$ of $V$ such that $F^{\infty }=E^{\infty }$ and therefore $F^{\unicode[STIX]{x1D714}}=E^{\unicode[STIX]{x1D714}}$ . In particular, $E^{\unicode[STIX]{x1D714}}$ is ${\mathcal{A}}(G)$ -tempered by Proposition 2. Now (1) applies.

Acknowledgement

The authors wish to thank Helge Glöckner for pointing out the discussed mistakes.

References

Gimperlein, H., Krötz, B. and Schlichtkrull, H., Analytic representation theory of Lie groups: general theory and analytic globalizations of Harish-Chandra modules , Compositio Math. 147 (2011), 15811607.CrossRefGoogle Scholar
Glöckner, H., Continuity of LF-algebra representations associated to representations of Lie groups , Kyoto J. Math. 53 (2013), 567595.Google Scholar