Banach Completions of Hybrid Shift-Spectral Algebra
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| Natura: | Recurso digital |
| Lingua: | inglese |
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2026
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| _version_ | 1866901231761358848 |
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| author | Daley, Ariel |
| author_facet | Daley, Ariel |
| contents | <p>Let \(\Omega_{r,s}:=(0,\infty)^r\times\mathbb{R}^s,\) \({\alpha}=(\alpha_1,\dots,\alpha_r)\in(0,1)^r,\) \(\Lambda\subset(\mathbb{C}_+)^s,\) and let \(e_{\mathbf{k},\lambda}(x,y) := \Big(\prod_{i=1}^r\frac{x_i^{k_i\alpha_i}}{\Gamma(k_i\alpha_i+1)}\Big)e^{\langle \lambda,y\rangle}\) \((\mathbf{k}\in\mathbb{N}_0^r,\ \lambda\in\Lambda)\) be the canonical hybrid basis introduced in the preceding paper on mixed regions. In the present paper we pass from the algebraic direct sum generated by this basis to weighted Banach completions. For $1\le p<\infty$ and a positive weight $\omega$ on $\mathbb{N}_0^r\times\Lambda$, we define the coefficient norm \( \Big\|\sum a_{\mathbf{k},\lambda}e_{\mathbf{k},\lambda}\Big\|_{p,\omega} := \Big(\sum |a_{\mathbf{k},\lambda}|^p\omega(\mathbf{k},\lambda)^p\Big)^{1/p}\) on the finite-support core and write $X_{\omega}^p$ for the resulting completion. Under a natural shift-admissibility condition on $\omega$, the partial Riemann--Liouville integrals and Caputo derivatives extend to bounded operators on $X_{\omega}^p$ and satisfy the same unilateral identities as in the algebraic model, \(C_iJ_i=I,\) \(J_iC_i=I-\Pi_i,\) as well as their higher-order analogues \(C^{\mathbf{m}}J^{\mathbf{m}}=I,\) \(J^{\mathbf{m}}C^{\mathbf{m}}=I-\Pi_{<\mathbf{m}}.\) Bounded spectral multipliers yield a diagonal functional calculus for the Weyl block, while arbitrary scalar symbols define closed densely defined operators on their maximal domains. In particular, standard multidimensional Weyl operators become closed diagonal operators on $X_{\omega}^p$. For geometric weights we further prove that hybrid Mittag--Leffler series become genuine vectors of the completion. These vectors are joint eigenvectors of the commuting Caputo tuple and of every spectral multiplier. Finally, we establish a Banach-space inversion theorem for mixed constant-coefficient operators of the form \(M_{\sigma_0}+\sum_{\mathbf{0}<\mathbf{m}\le \mathbf{M}}C^{\mathbf{m}}M_{\sigma_{\mathbf{m}}},\) under a uniform ellipticity and smallness condition, and we construct a fiberwise holomorphic model on a polydisk for geometric completions.</p> |
| format | Recurso digital |
| id | zenodo_https___doi_org_10_5281_zenodo_19132720 |
| institution | Zenodo |
| language | eng |
| publishDate | 2026 |
| publisher | Zenodo |
| record_format | zenodo |
| spellingShingle | Banach Completions of Hybrid Shift-Spectral Algebra Daley, Ariel fractional calculus Banach completion weighted sequence space Caputo derivative Weyl operator functional calculus Mittag-Leffler function MSC 46B45 MSC 26A33 MSC 47A13 MSC 47B37 <p>Let \(\Omega_{r,s}:=(0,\infty)^r\times\mathbb{R}^s,\) \({\alpha}=(\alpha_1,\dots,\alpha_r)\in(0,1)^r,\) \(\Lambda\subset(\mathbb{C}_+)^s,\) and let \(e_{\mathbf{k},\lambda}(x,y) := \Big(\prod_{i=1}^r\frac{x_i^{k_i\alpha_i}}{\Gamma(k_i\alpha_i+1)}\Big)e^{\langle \lambda,y\rangle}\) \((\mathbf{k}\in\mathbb{N}_0^r,\ \lambda\in\Lambda)\) be the canonical hybrid basis introduced in the preceding paper on mixed regions. In the present paper we pass from the algebraic direct sum generated by this basis to weighted Banach completions. For $1\le p<\infty$ and a positive weight $\omega$ on $\mathbb{N}_0^r\times\Lambda$, we define the coefficient norm \( \Big\|\sum a_{\mathbf{k},\lambda}e_{\mathbf{k},\lambda}\Big\|_{p,\omega} := \Big(\sum |a_{\mathbf{k},\lambda}|^p\omega(\mathbf{k},\lambda)^p\Big)^{1/p}\) on the finite-support core and write $X_{\omega}^p$ for the resulting completion. Under a natural shift-admissibility condition on $\omega$, the partial Riemann--Liouville integrals and Caputo derivatives extend to bounded operators on $X_{\omega}^p$ and satisfy the same unilateral identities as in the algebraic model, \(C_iJ_i=I,\) \(J_iC_i=I-\Pi_i,\) as well as their higher-order analogues \(C^{\mathbf{m}}J^{\mathbf{m}}=I,\) \(J^{\mathbf{m}}C^{\mathbf{m}}=I-\Pi_{<\mathbf{m}}.\) Bounded spectral multipliers yield a diagonal functional calculus for the Weyl block, while arbitrary scalar symbols define closed densely defined operators on their maximal domains. In particular, standard multidimensional Weyl operators become closed diagonal operators on $X_{\omega}^p$. For geometric weights we further prove that hybrid Mittag--Leffler series become genuine vectors of the completion. These vectors are joint eigenvectors of the commuting Caputo tuple and of every spectral multiplier. Finally, we establish a Banach-space inversion theorem for mixed constant-coefficient operators of the form \(M_{\sigma_0}+\sum_{\mathbf{0}<\mathbf{m}\le \mathbf{M}}C^{\mathbf{m}}M_{\sigma_{\mathbf{m}}},\) under a uniform ellipticity and smallness condition, and we construct a fiberwise holomorphic model on a polydisk for geometric completions.</p> |
| title | Banach Completions of Hybrid Shift-Spectral Algebra |
| topic | fractional calculus Banach completion weighted sequence space Caputo derivative Weyl operator functional calculus Mittag-Leffler function MSC 46B45 MSC 26A33 MSC 47A13 MSC 47B37 |
| url | https://doi.org/10.5281/zenodo.19132720 |