Sunday, August 23, 2015

real analysis - Convergence in measure and bounded Lp norm implies convergence in Lp




Let $11. fnf in measure and
2. supnNfnp<+ where fnp=(|fn|pdμ)1p is the Lp norm.
then fnf in Lp(μ).





I know that convergence in measure implies that there exists a subsequence converges a.e.,but how does it relate to convergence in Lp(μ).



Update:
Thanks for @carmichael561, the conclusion of the question was incorrect. It should be the convergence of integration.


Answer



The two conditions stated are not enough to imply convergence in Lp. Indeed, if X=[0,1] and μ is Lebesgue measure, then the sequence of functions
fn=n1[0,1n2]
converges to zero in measure and is bounded in L2 because
X|fn|2dμ=n21n2=1

for all n. But fn0 in L2.


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