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

Click For Summary
SUMMARY

The discussion focuses on writing elements in the space \( L^{p}(X,Y,\mu) \), where \( (X,\mathcal{A},\mu) \) is a complete σ-finite measure space and \( Y \) is a separable Banach space. The norm is defined as \( \| f \|_{p} = \left( \int_{X} \| f \|^{p} d\mu \right)^{\frac{1}{p}} \). The equivalence class of functions is defined such that \( f \sim_{p} g \) if \( \| f - g \|_{p} = 0 \), indicating that the functions agree almost everywhere. This definition is crucial for ensuring that the norm behaves correctly, avoiding non-zero vectors with a norm of zero.

PREREQUISITES
  • Understanding of complete σ-finite measure spaces
  • Familiarity with separable Banach spaces
  • Knowledge of \( L^{p} \) spaces and their properties
  • Proficiency in mathematical notation and norms, specifically the \( p \)-norm
NEXT STEPS
  • Study the properties of \( L^{p} \) spaces, focusing on convergence and completeness
  • Explore the concept of equivalence classes in functional analysis
  • Learn about the implications of the \( p \)-norm in different contexts
  • Investigate the relationship between measure theory and functional spaces
USEFUL FOR

Mathematicians, students of functional analysis, and researchers interested in measure theory and Banach spaces will benefit from this discussion.

moh salem
Messages
21
Reaction score
0
\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*}
 
Physics news on Phys.org
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.
 
As shown by this animation, the fibers of the Hopf fibration of the 3-sphere are circles (click on a point on the sphere to visualize the associated fiber). As far as I understand, they never intersect and their union is the 3-sphere itself. I'd be sure whether the circles in the animation are given by stereographic projection of the 3-sphere from a point, say the "equivalent" of the ##S^2## north-pole. Assuming the viewpoint of 3-sphere defined by its embedding in ##\mathbb C^2## as...

Similar threads

  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 1 ·
Replies
1
Views
3K
  • · Replies 5 ·
Replies
5
Views
1K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 4 ·
Replies
4
Views
1K