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| Format: | Preprint |
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2025
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| Online Access: | https://arxiv.org/abs/2511.01644 |
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| _version_ | 1866915593713614848 |
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| author | Keshari, Dinesh Kumar Nayak, Suryanarayan Pal, Avijit Paul, Bhaskar |
| author_facet | Keshari, Dinesh Kumar Nayak, Suryanarayan Pal, Avijit Paul, Bhaskar |
| contents | We obtain various characterizations of the fundamental operators of $Γ_{E(3; 3; 1, 1, 1)}$-contraction and $Γ_{E(3; 2; 1, 2)}$-contraction. We also demonstrate some important relations between the fundamental operators of a $Γ_{E(3; 3; 1, 1, 1)}$-contraction and a $Γ_{E(3; 2; 1, 2)}$-contraction. We describe functional models for \textit{pure $Γ_{E(3; 3; 1, 1, 1)}$-contraction} and \textit{pure $Γ_{E(3; 2; 1, 2)}$-contraction}. We give a complete set of unitary invariants for a pure $Γ_{E(3; 3; 1, 1, 1)}$-contraction and a pure $Γ_{E(3; 2; 1, 2)}$-contraction. We demonstrate the functional models for a certain class of completely non-unitary $Γ_{E(3; 3; 1, 1, 1)}$-contraction $\textbf{T} = (T_1, \dots, T_7)$ and completely non-unitary $Γ_{E(3; 2; 1, 2)}$-contraction $\textbf{S} = (S_1, S_2, S_3, \tilde{S}_1, \tilde{S}_2)$ which satisfy the following conditions: \begin{equation}\label{Condition 1} \begin{aligned} &T^*_iT_7 = T_7T^*_i \,\, \text{for} \,\, 1 \leqslant i \leqslant 6 \end{aligned} \end{equation} and \begin{equation}\label{Condition 2} \begin{aligned} &S^*_iS_3 = S_3S^*_i, \tilde{S}^*_jS_3 = S_3\tilde{S}^*_j \,\, \text{for} \,\, 1 \leqslant i, j \leqslant 2, \end{aligned} \end{equation} respectively. We also describe a functional model for a completely non-unitary tetrablock contraction $\textbf{T} = (A_1,A_2,P)$ that satisfies \begin{equation}\label{Condition 3} \begin{aligned} A^*_iP = PA^*_i \,\, \text{for $1 \leqslant i \leqslant 2$}. \end{aligned} \end{equation} By exhibiting counter examples, we show that such abstract model of tetrablock contraction, $Γ_{E(3; 3; 1, 1, 1)}$-contraction and $Γ_{E(3; 2; 1, 2)}$-contraction may not exist if we drop the hypothesis of the above equations, respectively.. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2511_01644 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Functional Models for $Γ_{E(3; 3; 1, 1, 1)}$-contraction, $Γ_{E(3; 2; 1, 2)}$-contraction and Tetrablock contraction Keshari, Dinesh Kumar Nayak, Suryanarayan Pal, Avijit Paul, Bhaskar Functional Analysis We obtain various characterizations of the fundamental operators of $Γ_{E(3; 3; 1, 1, 1)}$-contraction and $Γ_{E(3; 2; 1, 2)}$-contraction. We also demonstrate some important relations between the fundamental operators of a $Γ_{E(3; 3; 1, 1, 1)}$-contraction and a $Γ_{E(3; 2; 1, 2)}$-contraction. We describe functional models for \textit{pure $Γ_{E(3; 3; 1, 1, 1)}$-contraction} and \textit{pure $Γ_{E(3; 2; 1, 2)}$-contraction}. We give a complete set of unitary invariants for a pure $Γ_{E(3; 3; 1, 1, 1)}$-contraction and a pure $Γ_{E(3; 2; 1, 2)}$-contraction. We demonstrate the functional models for a certain class of completely non-unitary $Γ_{E(3; 3; 1, 1, 1)}$-contraction $\textbf{T} = (T_1, \dots, T_7)$ and completely non-unitary $Γ_{E(3; 2; 1, 2)}$-contraction $\textbf{S} = (S_1, S_2, S_3, \tilde{S}_1, \tilde{S}_2)$ which satisfy the following conditions: \begin{equation}\label{Condition 1} \begin{aligned} &T^*_iT_7 = T_7T^*_i \,\, \text{for} \,\, 1 \leqslant i \leqslant 6 \end{aligned} \end{equation} and \begin{equation}\label{Condition 2} \begin{aligned} &S^*_iS_3 = S_3S^*_i, \tilde{S}^*_jS_3 = S_3\tilde{S}^*_j \,\, \text{for} \,\, 1 \leqslant i, j \leqslant 2, \end{aligned} \end{equation} respectively. We also describe a functional model for a completely non-unitary tetrablock contraction $\textbf{T} = (A_1,A_2,P)$ that satisfies \begin{equation}\label{Condition 3} \begin{aligned} A^*_iP = PA^*_i \,\, \text{for $1 \leqslant i \leqslant 2$}. \end{aligned} \end{equation} By exhibiting counter examples, we show that such abstract model of tetrablock contraction, $Γ_{E(3; 3; 1, 1, 1)}$-contraction and $Γ_{E(3; 2; 1, 2)}$-contraction may not exist if we drop the hypothesis of the above equations, respectively.. |
| title | Functional Models for $Γ_{E(3; 3; 1, 1, 1)}$-contraction, $Γ_{E(3; 2; 1, 2)}$-contraction and Tetrablock contraction |
| topic | Functional Analysis |
| url | https://arxiv.org/abs/2511.01644 |