Let $i:H \to G$ be a homomorphism of compact Lie groups. The induced representation $\iota_*V := \mathrm{Map}^H(G,V)$ of an $H$-representation $V$ does not give an element of the representation ring $R(G)$ of $G$ (because $\iota_*V$ is usually infinite-dimensional).

But $\iota_*V$ is an element of a larger group $R.\!(G)$. Here $R.\!(G)$ is defined to be the group of maps from the set $\hat G$ of irreducible representations of $G$ to $\mathbb Z$. The abelian group $R.\!(G)$ is naturally isomorphic to the dual group $\mathrm{Hom}(R(G),\mathbb Z)$.

($\ast$) By Peter-Weyl theorem, $\iota_*V$ is uniquely described as the direct sum $\oplus W_i^{\oplus m_i}$ of irreducible $G$-representations. Here $m_i$ is the multiplicity of $W_i$ and $W_i$ is an irreducible $G$-representation. Then we define $\iota_*V:\hat G \to \mathbb Z$ by $$(\iota_*V)(P) = \begin{cases}m_i&P=W_i \text{ for some } i\\ 0&\text{else}\end{cases}\quad(P \in \hat G).$$ So we obtain $\iota_*:R(H) \to R.\!(G)$.

On the other hand, the pullback of representations via $i$ gives rise to a homomorphism $i^*:R(G) \to R(H)$. Taking its transpose, we obtain a homomorphism $i_*:R.\!(H) \to R.\!(G)$.

Now we can naturally embed $R(H)$ into $R.\!(H)$. (Take the irreducible decomposition of an $H$-representation, then assign to each irreducible $H$-representation its multiplicity.)

**Question: Does $\iota_*:R(H) \to R.\!(G)$ agree with $i_*:R(H) \to R.\!(G)$?**

**Notes**:

This question arose when I was reading the paper "The representation ring of a compact Lie group" by Segal. He does not seem to give an explicit definition of $\iota_*$. (It is unclear at least for me.) I suspect that the above paragraph ($\ast$) is wrong.

I moved the answer which was here below.

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