Compact embedding and strong convergence

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    Compact Convergence
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SUMMARY

The discussion centers on the relationship between compact embeddings and convergence properties in functional analysis. Specifically, if X is compactly embedded in Y and a sequence f_n in X converges weakly in X and strongly in Y to a function f in X, then f_n converges strongly to f in X due to the compactness of the embedding. The key takeaway is that the compactness of the embedding is sufficient for strong convergence in X when weak convergence in X and strong convergence in Y are established.

PREREQUISITES
  • Understanding of compact embeddings in functional analysis
  • Knowledge of weak and strong convergence concepts
  • Familiarity with sequences and limits in topological spaces
  • Basic principles of functional analysis and Banach spaces
NEXT STEPS
  • Study the implications of compactness in functional analysis
  • Explore the differences between weak and strong convergence
  • Investigate examples of compactly embedded spaces
  • Learn about the role of Banach and Hilbert spaces in convergence theory
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Mathematicians, particularly those specializing in functional analysis, graduate students studying topology, and researchers exploring convergence properties in compact spaces.

NSAC
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Let X be compactly embedded in Y. Assume also that
there is a sequence f_n in X such that
f_n converges to f weakly in X and strongly in Y to some function f in X.
Can we say that f_n converges to f strongly in X?
 
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Yes, it's due to the compactness of the embedding.
 
Eynstone said:
Yes, it's due to the compactness of the embedding.

Which assumption together with compactness imply this? Weak convergence in X or strong convergence in Y or both? Could you elaborate more?
 

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