Proving Another Vector Norm on C[0,1]

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In summary, the function \| \|: C[0,1] \rightarrow R defined by \|f\| = |f(1) - f(0)| does not define a norm on C[0,1], as it fails the second axiom.
  • #1
gtfitzpatrick
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Homework Statement



does the function [tex]
\| \|: C[0,1] \rightarrow
[/tex] R defined by [tex]
\|f \|= |f(1)- f(0)|
[/tex] define a norm on C[0,1]. if it does prove all axioms if not show axiom which fails

The Attempt at a Solution



i don't really understand the question. i know the 4 axioms of a norm but i don't know how to use the info given to prove or disprove them. is the question telling me that x has to be either 0 or 1 and y has to be either 0 or 1.
 
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  • #2
wait so its actually telling me its a straight line at y=1 between the points x=0 and x=1. so f(1) = 1 and f(0) = 1

so axiom 2 fails [tex]

\|f \| = 0

[/tex] iff f = [tex] \vec 0 [/tex] but [tex]

\|f \|= |f(1)- f(0)| = |1- 1| = 0

[/tex]
 
  • #3
Your words and reasoning seem garbled, but your counterexample is correct: [tex]\|f\| = |f(1) - f(0)|[/tex] does not define a norm on [tex]C[0,1][/tex], because if [tex]f(x) = 1[/tex] is the constant function then [tex]\|f\| = |1 - 1| = 0[/tex] even though [tex]f \neq 0[/tex].
 

1. What is a vector norm in the context of C[0,1]?

In mathematics, a vector norm is a mathematical function that assigns a positive length or size to each vector in a vector space. In the context of C[0,1], which represents the set of continuous functions on the interval [0,1], a vector norm measures the size or magnitude of a function in this space.

2. Why is it important to prove another vector norm on C[0,1]?

Proving another vector norm on C[0,1] allows for more flexibility and options in measuring the size or magnitude of a function in this space. Different vector norms may be useful for different applications or contexts, and having multiple options can provide a more comprehensive understanding of the functions in C[0,1].

3. How is a vector norm on C[0,1] different from a norm in other vector spaces?

A vector norm on C[0,1] may have different properties or definitions compared to norms in other vector spaces. For example, the norms in C[0,1] may be specific to the space of continuous functions, while norms in other vector spaces may be defined for more general types of vectors. Additionally, the specific properties and behaviors of a norm on C[0,1] may differ from those of norms in other vector spaces.

4. What is the process for proving another vector norm on C[0,1]?

The process for proving another vector norm on C[0,1] may vary depending on the specific norm being considered. However, in general, the proof will involve showing that the norm satisfies the necessary properties, such as sublinearity and positive definiteness, for it to be considered a valid norm. This may involve using mathematical techniques such as the triangle inequality and proving convergence of sequences.

5. What are some examples of vector norms on C[0,1]?

Some common examples of vector norms on C[0,1] include the sup norm, the L1 norm, and the L2 norm. The sup norm, also known as the maximum norm, measures the maximum absolute value of a function over the interval [0,1]. The L1 norm, also known as the Manhattan norm, measures the sum of the absolute values of a function over the interval [0,1]. The L2 norm, also known as the Euclidean norm, measures the square root of the sum of squares of a function over the interval [0,1]. These are just a few examples, as there are many possible vector norms that can be defined on C[0,1].

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