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Dynamical systems method (DSM) for unbounded operators (0)

by A G Ramm
Venue:Proc.Amer. Math. Soc
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The Dynamical Systems Method for solving nonlinear equations with monotone operators

by N. S. Hoang, A. G. Ramm
"... A review of the authors’s results is given. Several methods are discussed for solving nonlinear equations F(u) = f, where F is a monotone operator in a Hilbert space, and noisy data are given in place of the exact data. A discrepancy principle for solving the equation is formulated and justified. V ..."
Abstract - Cited by 15 (12 self) - Add to MetaCart
A review of the authors’s results is given. Several methods are discussed for solving nonlinear equations F(u) = f, where F is a monotone operator in a Hilbert space, and noisy data are given in place of the exact data. A discrepancy principle for solving the equation is formulated and justified. Various versions of the Dynamical Systems Method (DSM) for solving the equation are formulated. These methods consist of a regularized Newton-type method, a gradient-type method, and a simple iteration method. A priori and a posteriori choices of stopping rules for these methods are proposed and justified. Convergence of the solutions, obtained by these methods, to the minimal norm solution to the equation F(u) = f is proved. Iterative schemes with a posteriori choices of stopping rule corresponding to the proposed DSM are formulated. Convergence of these iterative schemes to a solution to equation F(u) = f is justified. New nonlinear differential inequalities are derived and applied to a study of large-time behavior of solutions to evolution equations. Discrete versions of these inequalities are established.

Dynamical systems gradient method for solving nonlinear . . .

by N. S. Hoang , A. G. Ramm - ACTA APPL MATH
"... A version of the Dynamical Systems Gradient Method for solving ill-posed nonlinear monotone operator equations is studied in this paper. A discrepancy principle is proposed and justified. A numerical experiment was carried out with the new stopping rule. Numerical experiments show that the proposed ..."
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A version of the Dynamical Systems Gradient Method for solving ill-posed nonlinear monotone operator equations is studied in this paper. A discrepancy principle is proposed and justified. A numerical experiment was carried out with the new stopping rule. Numerical experiments show that the proposed stopping rule is efficient. Equations with monotone operators are of interest in many applications.
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...[10]. From (15) and(16), one gets the following estimate: Lemma 8 Suppose a(t) = constants. Then d2 ( 1 − 2 2b cθ d2 ) ∫ t ‖Vδ‖≤‖V ‖+ δ a d (c+t) b , ϕ(t) = ∫ t 0 0 ‖V ‖≤‖y‖. (16) a 2 (s) 2 δ ≤‖y‖+ . =-=(17)-=- a 1 ds where b ∈ (0, ], d and c are positive 4 eϕ(s) eϕ(t) ds < , ∀t >0, θ= 1 − 2b>0. (18) (s + c) 3b (c + t) b480 N.S. Hoang, A.G. Ramm Proof We have ∫ t ϕ(t) = 0 d2 ds = 2(c + s) 2b where θ := 1 −...

AN ITERATIVE SCHEME FOR SOLVING NONLINEAR EQUATIONS WITH MONOTONE OPERATORS

by N. S. Hoang, A. G. Ramm
"... An iterative scheme for solving ill-posed nonlinear operator equations with monotone operators is introduced and studied in this paper. A discrete version of the Dynamical Systems Method (DSM) algorithm for stable solution of ill-posed operator equations with monotone operators is proposed and its c ..."
Abstract - Cited by 11 (6 self) - Add to MetaCart
An iterative scheme for solving ill-posed nonlinear operator equations with monotone operators is introduced and studied in this paper. A discrete version of the Dynamical Systems Method (DSM) algorithm for stable solution of ill-posed operator equations with monotone operators is proposed and its convergence is proved. A discrepancy principle is proposed and justified. A priori and a posteriori stopping rules for the iterative scheme are formulated and justified.
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... In [6] a general approach to construction of convergent iterative processes for solving (1.1) on the basis of the DSM is developed. Some results on the DSM and its applications one finds in [2], [6]–=-=[13]-=-. In [3]–[6] and references therein methods for solving ill-posed problems are discussed. Although the DSM is presented in detail in the monograph [6], we briefly give its main idea for convenience of...

A NEW VERSION OF THE DYNAMICAL SYSTEMS METHOD (DSM) FOR SOLVING NONLINEAR EQUATIONS WITH MONOTONE OPERATORS

by N. S. Hoang, A. G. Ramm
"... ..."
Abstract - Cited by 7 (5 self) - Add to MetaCart
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Dynamical systems method for solving linear finite-rank operator equations

by N. S. Hoang, A. G. Ramm , 2009
"... ..."
Abstract - Cited by 6 (3 self) - Add to MetaCart
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Dynamical systems gradient method for solving ill-conditioned linear algebraic systems

by N. S. Hoang, A. G. Ramm
"... ..."
Abstract - Cited by 5 (2 self) - Add to MetaCart
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...n of (6). Theorem 3 Assume that ‖Au0 − fδ‖ >Cδ. The solution tδ to the equation does exist, is unique, and Proof Denote and One has h(t) := ‖Auδ(t) − fδ‖=Cδ, 1 <C= const, (16) lim δ→0 ‖uδ(tδ) − y‖=0. =-=(17)-=- vδ(t) := Auδ(t) − fδ, T := A ∗ A, Q = AA ∗ wδ(t) := uδ(t) − y, w0 := u0 − y. d dt ‖vδ(t)‖ 2 = 2Re〈A˙uδ(t), Auδ(t) − fδ〉 = 2Re〈A[−A ∗ (Auδ(t) − fδ)],Auδ(t) − fδ〉 =−2‖A ∗ vδ(t)‖ 2 ≤ 0. (18) Thus, ‖vδ(t...

Dynamical Systems Method (DSM) for solving equations with monotone operators without smoothness assumptions on F'(u)

by N. S. Hoang, A. G. Ramm - JOURNAL OF MATHEMATICAL ANALYSIS AND APPLICATIONS , 2010
"... ..."
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Dynamical Systems Method (DSM) for solving nonlinear operator equations in Banach spaces

by A G Ramm
"... Let F (u) = h be an operator equation in a Banach space X with Gateaux differentiable norm, ‖F ′ (u) − F ′ (v) ‖ ≤ ω(‖u − v‖), where ω ∈ C([0, ∞)), ω(0) = 0, ω(r) is strictly growing on [0, ∞). Denote A(u):= F ′ (u), where F ′ (u) is the Fréchet derivative of F, and Aa: = A + aI. Assume that (*) ..."
Abstract - Cited by 1 (1 self) - Add to MetaCart
Let F (u) = h be an operator equation in a Banach space X with Gateaux differentiable norm, ‖F ′ (u) − F ′ (v) ‖ ≤ ω(‖u − v‖), where ω ∈ C([0, ∞)), ω(0) = 0, ω(r) is strictly growing on [0, ∞). Denote A(u):= F ′ (u), where F ′ (u) is the Fréchet derivative of F, and Aa: = A + aI. Assume that (*) ‖A −1 a (u) ‖ ≤ c1 |a | b, |a |&gt; 0, b&gt; 0, a ∈ L. Here a may be a complex number, and L is a smooth path on the complex a-plane, joining the origin and some point on the complex a−plane, 0 &lt; |a | &lt; ɛ0, where ɛ0&gt; 0 is a small fixed number, such that for any a ∈ L estimate (*) holds. It is proved that the DSM (Dynamical Systems Method) ˙u(t) = −A −1 a(t) (u(t))[F (u(t)) + a(t)u(t) − f], du u(0) = u0, ˙u = dt, converges to y as t → +∞, where a(t) ∈ L, F (y) = f, r(t): = |a(t)|, and r(t) = c4(t + c2) −c3, where cj&gt; 0 are some suitably chosen constants, j = 2, 3, 4. Existence of a solution y to the equation F (u) = f is assumed. It is also assumed that the equation F (wa) + awa − f = 0 is uniquely solvable for any f ∈ X, a ∈ L, and lim|a|→0,a∈L ‖wa − y ‖ = 0.

DSM for solving linear operator equations

by N. S. Hoang
"... N. S. Hoang DSM for solving linear operator equations ..."
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N. S. Hoang DSM for solving linear operator equations
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