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Showing 1 to 20 of 71 for “"Differential operators"”.
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Differential operators on varieties,
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mathematics, 1972.
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Global solvability of invariant differential operators.
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mathematics, 1978
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Topics in spectral theory of differential operators /
… of self-adjoint extensions of partial differential operators, and computing the number of negative eigenvalues for bounded from below operators with compact resolvents. In the first part of this thesis we derive a Weyl-type asymptotic formula and a bound for the eigenvalue counting …
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Rings of differential operators and étale homomorphisms
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mathematics, 1991.
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Positivity properties associated with linear differential operators
… positivity results associated with linear differential operators of the form (Ly)(t) = a₂(t)y''(t) + a₁(t)y¹(t) + a₀(t)y(t), where a₂(t), a₁(t) and a₀(t) are real-analytic in some interval I and where a₂(t) > 0 for t ε I. We call a function f ε C<sup>∞</sup> L-positive at t₀ ε I if it …
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Lie derivations on rings of differential operators
Derivations on rings of differential operators are studied. In particular, we ask whether Lie derivations are forced to be associative derivations. This is established for the Weyl algebras, which provides the details of a theorem of A. Joseph. The ideas are extended to localizations of Weyl …
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Closability of differential operators and subjordan operators
A (bounded linear) operator J on a Hilbert space is said to be jordan if J = S + N where S = S* and N² = 0. The operator T is subjordan if T is the restriction of a jordan operator to an invariant subspace, and pure subjordan if no nonzero restriction of T to an invariant subspace is jordan. The …
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Lie Algebras of Differential Operators and D-modules
In our thesis we study the algebras of differential operators in algebraic and geometric terms. We consider two problems in which the algebras of differential operators naturally arise. The first one deals with the algebraic structure of differential and pseudodifferential operators. We define the …
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Two-dimensional twisted sigma models and chiral differential operators
… mathematical theories involving a??Chiral Differential Operatorsa?? (or CDOa??s) defined and constructed by mathematicians in recent times. In this thesis, we consider the following four cases.Firstly, we study a twisted version of the two-dimensional (0; 2) heterotic sigma model on a …
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Rational matrix differential operators and integrable systems of PDEs
… of evolution PDEs ut = F(u), where F lies in a differential algebra of functionals V and u = (U1, ... , ul) depends on one space variable x and time t, is to be part of an infinite hierarchy of generalized symmetries. Recall that V carries a Lie algebra bracket {F, G} = XF(G) - XG(F), where XF …
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Perturbations of Partial Differential Operators by Means of Boundary Conditions
Made available in DSpace on 2014-12-14T13:09:40Z (GMT). No. of bitstreams: 1 7913629.pdf: 2041407 bytes, checksum: 5ffcd48fdc7afa5e489878ade2bacf92 (MD5) Previous issue date: 1978
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On quantum Euclidean spaces: Continuous deformation and pseudo-differential operators
… we study the continuous deformation and Pseudo-differential calculus of quantum Euclidean spaces. After reviewing the basic definitions and representation theory of quantum Euclidean spaces in Chapter 1, we prove in Chapter 2 a Lip^(1/2) continuous embedding of the family of quantum Euclidean …
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Residue functionals on the algebra of adiabatic pseudo-differential operators
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Mathematics, 1999.
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Variational convergence of nonlinear partial differential operators on varying Banach spaces
… verschiedene Typen von quasi-linearen partiellen Differentialoperatoren, welche einen Banach-Raum $X$ in dessen Dualraum $X^ast$ abbilden. Sämtliche dieser Operatoren werden vollständig durch variationelle Methoden mittels unterhalbstetiger konvexer Funktionale auf einem in $X$ echt eingebetteten …
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Approximation of Elements of Exponentials of Differential Operators With Rational Quadrature
… of approximations of elements of exponentials of differential operators, by using a rational function, instead of a polynomial function, as the interpolating function. Since a rational function behaves more like a decaying exponential function, it seems logical that the approximation should be …
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Local Factorization of Multidimensional Differential Operators to Optimize Implicit Solution Methods
Solving multidimensional differential operators using implicit finite-difference methods involves a computationally intensive step of calculating the solution to a system that involves both the current and future state of the system. If a linear operator can be expressed as an affine combination of …
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Degenerate elliptic second-order differential operators with bounded complex-valued coefficients
… properties for degenerate elliptic second-order differential operators in divergence form with bounded complex-valued coefficients. The main contribution of the thesis is in two parts. In one dimension we characterise when the space of test functions is a core for these operators. In higher …
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