Search for dissertations about: "Difference algebra"
Showing result 1 - 5 of 12 swedish dissertations containing the words Difference algebra.
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1. Reordering in Noncommutative Algebras, Orthogonal Polynomials and Operators
Abstract : The main object studied in this thesis is the multi-parametric family of unital associative complex algebras generated by the element $Q$ and the finite or infinite set $\{S_j\}_{j\in J}$ of elements satisfying the commutation relations $S_jQ=\sigma_j(Q)S_j$, where $\sigma_j$ is a polynomial for all $j\in J$. A concrete representation is given by the operators $Q_x(f)(x)=xf(x)$ and $\alpha_{\sigma_j}(f)(x)=f(\sigma_j(x))$ acting on polynomials or other suitable functions. READ MORE
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2. Quasi-Lie Algebras and Quasi-Deformations. Algebraic Structures Associated with Twisted Derivations
Abstract : This thesis introduces a new deformation scheme for Lie algebras, which we refer to as ?quasi-deformations? to clearly distinguish it from the classical Grothendieck-Schlessinger and Gers-tenhaber deformation schemes. The main difference is that quasi-deformations are not in gene-ral category-preserving, i.e. READ MORE
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3. Structural Reformulations in System Identification
Abstract : In system identification, the choice of model structure is important and it is sometimes desirable to use a flexible model structure that is able to approximate a wide range of systems. One such model structure is the Wiener class of systems, that is, systems where the input enters a linear time-invariant subsystem followed by a time-invariant nonlinearity. READ MORE
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4. Semigroups of Sets Without the Baire Property In Finite Dimensional Euclidean Spaces
Abstract : A semigroup of sets is a family of sets closed under finite unions. This thesis focuses on the search of semigroups of sets in finite dimensional Euclidean spaces Rn, n ≥ 1, which elements do not possess the Baire property, and on the study of their properties. READ MORE
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5. Blow-ups and normal bundles in derived algebraic geometry and beyond
Abstract : The main part of this thesis, Part II, consists of four papers. A summary and background is provided in Part I.Paper A introduces blow-ups of derived schemes in arbitrary centers, which is a generalization of the quasi-smooth case from [KR19]. READ MORE