Mosco convergence

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In mathematical analysis, Mosco convergence, is a notion of convergence for functionals that is used in nonlinear analysis and set-valued analysis. It is a particular case of Γ-convergence. Mosco convergence is sometimes phrased as “weak Γ-liminf and strong Γ-limsup” convergence since it uses both the weak and strong topologies on a topological vector space X.

Mosco convergence is named after Italian mathematician Umberto Mosco, a current Harold J. Gay[1] professor of mathematics at Worcester Polytechnic Institute.

Definition

Let X be a topological vector space and let X denote the dual space of continuous linear functionals on X. Let Fn : X  [0, +∞] be functionals on X for each n = 1, 2, ... The sequence (or, more generally, net) (Fn) is said to Mosco converge to another functional F : X  [0, +∞] if the following two conditions hold:

  • lower bound inequality: for each sequence of elements xn  X converging weakly to x  X,
\liminf _{{n\to \infty }}F_{{n}}(x_{{n}})\geq F(x);
  • upper bound inequality: for every x  X there exists an approximating sequence of elements xn  X, converging strongly to x, such that
\limsup _{{n\to \infty }}F_{{n}}(x_{{n}})\leq F(x).

Since lower and upper bound inequalities of this type are used in the definition of Γ-convergence, Mosco convergence is sometimes phrased as “weak Γ-liminf and strong Γ-limsup” convergence. Mosco convergence is sometimes abbreviated to M-convergence and denoted by

{\mathop  {{\text{M-lim}}}}_{{n\to \infty }}F_{{n}}=F{\text{ or }}F{\xrightarrow[ {n\to \infty }]{{\mathrm  {M}}}}F.

References

  • Mosco, Umberto (1967). "Approximation of the solutions of some variational inequalities". Ann. Scuola Normale Sup. (Pisa) 21: 373394. 
  • Mosco, Umberto (1969). "Convergence of convex sets and of solutions of variational inequalities". Advances in Mathematics 3 (4): 510585. doi:10.1016/0001-8708(69)90009-7. 
  • Borwein, Jonathan M.; Fitzpatrick, Simon (1989). "Mosco convergence and the Kadec property". Proc. Amer. Math. Soc. (American Mathematical Society) 106 (3): 843851. doi:10.2307/2047444. JSTOR 2047444. 
  • Mosco, Umberto. "Worcester Polytechnic Institute Faculty Directory". 

Notes

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