Hölder's Theorem & Manipulating 1/p + 1/q = 1

  • Thread starter zxh
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In summary, the conversation discusses how to manipulate the equation 1/p + 1/q = 1 to get the equation (p-1)(q-1) = 1. The suggested solution is to multiply both sides by pq, then subtract 1, and factor. The connection between the logarithm and this equation is also briefly mentioned.
  • #1
zxh
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Homework Statement



How do you get from 1/p +1/q = 1 to (p-1)(q-1) = 1? (http://de.wikipedia.org/wiki/Konjugation_%28Reelle_Zahlen%29" )

Homework Equations



Is log(xy) = log(x) + log(y) in any way related to this, i.e the rewritten subject title?

The Attempt at a Solution



Manipulate[
ContourPlot[x + y == x*y, {x, -m, m}, {y, -m, m},
PlotRange -> Automatic], {m, -100, 100}]

TIA!
 
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  • #2
Multiply out and compare. Logarithms have nothing to do with the equation you mentioned, but you might be using the logarithm to prove some other aspect of Hölders inequality.
 
  • #3
zxh said:
How do you get from 1/p +1/q = 1 to (p-1)(q-1) = 1? (http://de.wikipedia.org/wiki/Konjugation_%28Reelle_Zahlen%29" )

You can get the second equation from the first one by multiplying both sides of the first equation by pq, then subtracting 1, and factoring. Try, it is fun. :smile:

ehild
 
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  • #4
Alright, makes me look tired, but i thought the similarity with the logarithm was too salient not to connect the two.
 

What is Hölder's Theorem?

Hölder's Theorem is a mathematical theorem that provides a condition for when two functions can be multiplied and still preserve their integrability. It states that if two functions, f and g, are integrable on a measure space, then their product, fg, is also integrable if the exponents of f and g satisfy the inequality p + q = 1.

What is 1/p + 1/q = 1?

This equation is known as the Hölder conjugate or dual exponent relationship. It is a key component of Hölder's Theorem, and it relates the exponents of two functions in order to determine their integrability when multiplied together.

How is 1/p + 1/q = 1 used in mathematics?

This equation is used in various mathematical fields, including analysis, functional analysis, and measure theory. It is an important tool in proving the integrability of functions and is also used in the study of convex functions and inequalities.

What is the significance of Hölder's Theorem?

Hölder's Theorem is significant because it allows mathematicians to determine the integrability of a product of two functions based on the exponents of those functions. This is useful in many areas of mathematics, including in the study of partial differential equations and in the development of new mathematical theories.

Are there any limitations to Hölder's Theorem?

Yes, Hölder's Theorem has limitations. It only applies to functions defined on a measure space and does not take into account the behavior of the functions outside of the measure space. It also does not provide information about the behavior of the integrals of the functions, only their integrability. Additionally, it does not apply to all types of integrals, such as improper integrals.

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