Writing Elements in $L^p(X,Y,\mu)$ Mathematically

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Discussion Overview

The discussion revolves around the mathematical representation of elements in the space $L^{p}(X,Y,\mu)$, focusing on the definition and notation of equivalence classes of functions within this context. The scope includes theoretical aspects of functional analysis and measure theory.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant seeks clarification on how to write elements of $L^{p}(X,Y,\mu)$ mathematically, specifically regarding the notation for equivalence classes.
  • Another participant suggests that the question may pertain to standard notation for equivalence classes of functions or the definition of such classes with respect to the $||\cdot||_p$ norm.
  • A participant defines the equivalence relation as $f \sim_{p} g \iff || f - g ||_p = 0$.
  • It is noted that two functions are equivalent if they agree almost everywhere, which is necessary for the norm to be valid.
  • Another participant emphasizes that without this condition, non-zero vectors could have a norm of zero.

Areas of Agreement / Disagreement

Participants express different aspects of the definition of equivalence classes, and while there is some agreement on the necessity of functions agreeing almost everywhere, the discussion does not reach a consensus on the notation or the precise definition.

Contextual Notes

The discussion highlights potential ambiguities in notation and definitions related to equivalence classes in the context of $L^{p}$ spaces, which may depend on specific interpretations or conventions in functional analysis.

moh salem
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\begin{equation*}Let\text{ } (X,\mathcal{A} ,\mu ) \text{ }be \text{ }a \text{ }complete\text{ } \sigma -finite\text{ } measure\text{ } space \\and \text{ }Y \text{ }be \text{ }a \text{ }separable\text{ } Banach\text{ } space\text{ } supplied \text{ }with \text{ }the \text{ }norm\text{ } \left\Vert .\right\Vert . \\For \text{ }every \text{ }p,1\leq p<\infty \text{ } let \text{ } L^{p}(X,Y,\mu ) \text{ }be \text{ }the \text{ }vector \text{ }space \text{ }of \text{ }all \text{ }equivalence \text{ }classes\\ with \text{ }the \text{ }norm \text{ }\left\Vert f\right\Vert _{p}=(\int_{X}\left\Vert f\right\Vert ^{^{^{p}}}d\mu )^{\frac{1}{p}}. \\
Question: \text{ }How \text{ }do \text{ }I \text{ }writing \text{ }elements\text{ } L^{p}(X,Y,\mu ) \text{ }mathematically?\\
Thanks
\end{equation*}
 
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You need to edit the LaTex so the phrase "of all equivalence classes" shows up completely. As it is, the word "classes" is not visible.

Is your question: "What is a standard notation for an equivalence class of functions?".

Or are you asking "What is the definition of an equivalence class of functions with respect to the ||\ ||_p norm?"
 
"What is the definition of an equivalence class of functions with respect to the || ||p norm?"
 
My opinion: f\ =_{p} \ g\iff \ || f - g ||_p = 0.
 
You can say it in terms of the p-norm, but that's equivalent to the fact that the functions agree almost everywhere. So, a function is equivalent to another function if they agree almost everywhere. This is what you need for the norm to actually be a norm.
 
Like homeo. said, otherwise you will have non-zero vectors with norm zero.
 

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