Integration to d density function

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Discussion Overview

The discussion revolves around the integration of a specific function related to a density function, particularly focusing on the expression Int(from 0 to x) (1-F(x-t)) dF(x). Participants explore the implications of this integration in the context of probability and stochastic processes.

Discussion Character

  • Mathematical reasoning
  • Technical explanation
  • Exploratory

Main Points Raised

  • One participant expresses difficulty in calculating the integral Int(from 0 to x) (1-F(x-t)) dF(x).
  • Another participant clarifies that dF(x) can be expressed as (dF/dx)dx, suggesting a method to approach the integration.
  • A participant notes the need to multiply the integrand by the density f=dF/dx and integrate over dx, while also expressing uncertainty about deriving the expectation without knowing the density.
  • One participant poses a series of questions regarding the integral of various functions with respect to different variables, indicating a playful exploration of integration concepts.
  • Another participant mentions that the integral of F(s) with respect to F(s) relates to convolution, while also noting the presence of x in both the integrand and the limit, which complicates the integration.
  • A later reply indicates that the participant found the answer in their stochastic course material, providing a formula for the distribution of the sum of two independent random variables.

Areas of Agreement / Disagreement

The discussion features multiple competing views and approaches to the integration problem, with no consensus reached on the best method or solution. Participants express differing levels of understanding and interpretation of the integration process.

Contextual Notes

Participants highlight the complexity of the integration due to the presence of x in both the integrand and the limits, as well as the dependency on the unknown density function.

benoardo
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I have a problem with an integration, namely:

Int(from 0 to x) (1-F(x-t)) dF(x)

and do not know how to calculate...:-(
 
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If it help,s dF(x) = (dF/dx)dx
 
It helps, but that mean to multiply the integrand by the density f=dF/dx and then integrate over dx, so like how to derive the expectation...

but another problem is, that I do not know the density and need to have a result within F(x)
 
Well, you can do it, though you do'nt think you can. so let#'s play a littel game.

What's the integral of 1 with respect to x? 1 wrt y? 1 wrt F(x)?

Now what's the integral of x wrt x? y wrt y, F(s) wrt F(s)?

Note, I don't think you want an x in the integrand and in the limit.
 
That's almost all clear but in my book i read that F(s) wrt F(s) is something like F(s)*F(s) which stands here for the convolution...
And i have a x in the itegrand as well as in the limit.
As I said before: int(0 to x) 1-F(x-t) wrt F(t), sorry so you are write, it is F(t) not F(x)!
 
Thank you very much for your support, but yesterday i found the answer in my stochastic I scriptum...if someone is interested in:

Let x, y be independent rvs with dfs F and G then holds for the distribuntion of the sum x+y:

H(a)=P(x+y<=a)=int F(a-v)dG(v).
 

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