L^p spaces are not equivalent for infinite measure sets

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Homework Help Overview

The discussion revolves around identifying a function that belongs to one L^p space but not to another, specifically for different values of p and q. The context is within the study of L^p spaces in functional analysis, particularly concerning infinite measure sets.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • Participants explore the idea of finding a function that is in L^1 but not in L^2, considering the implications of compact support. There is also a suggestion to find a function that behaves differently when raised to different powers.

Discussion Status

The conversation is ongoing, with participants sharing ideas and questioning the validity of suggested functions. Some guidance has been offered regarding the choice of functions, but no consensus has been reached on a suitable example.

Contextual Notes

There is an emphasis on the challenge of proving the properties of the functions in relation to their membership in the L^p spaces, particularly for functions defined on the real numbers.

JasonJo
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Find a function f such that f is in L^P(R) but not in L^Q(R) for p not equal to q, where R is the set of real numers.

I'm guessing I need to find a function that only blows up when it is raised to the qth power, but I am having some difficulty proving this.
 
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Try finding some function f that's in L^1 but not in L^2. To make things easier, you can choose a compactly-supported f.
 
I suppose just f = sin would do!
 
It wouldn't, because sin isn't in any L^p(R) space. :-p
 
Oh, right!:blushing:
 

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