Are All Functions Dependent on Each Other?

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Discussion Overview

The discussion revolves around the concept of independence between functions, specifically addressing when two functions, y1 = f1(x) and y2 = f2(x), can be considered independent or dependent on each other. The scope includes theoretical considerations and definitions related to function independence, linear independence, and the implications of the Wronskian determinant.

Discussion Character

  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant suggests that functions y1 and y2 are never independent because y2 can be expressed as a function of y1, implying a dependency between any two functions.
  • Another participant introduces the concept of linearly-independent functions, noting that functions with a vanishing Wronskian are not linearly independent.
  • A participant questions the original post's understanding of independence, indicating that the term may not align with the mathematical definition of linear independence.
  • Further clarification is sought regarding the meaning of independence in the context of the discussion, with emphasis on the need for precise definitions before addressing the question of function independence.

Areas of Agreement / Disagreement

Participants express differing views on the concept of independence among functions, with some arguing for a general dependency and others emphasizing the distinction of linear independence. The discussion remains unresolved regarding the precise definitions and implications of function independence.

Contextual Notes

There is a lack of clarity regarding the definitions of independence being used, and participants highlight the need for a more rigorous framework to discuss the relationships between functions. The discussion also touches on the mathematical properties of the Wronskian, which may not be fully understood by all participants.

Heirot
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When are to functions y1 = f1(x) and y2 = f2(x) independent? It would apper never, because, we can always write x = f1-1 (y1), and therefore y2 is a function of y1. Every function is dependent of any other function. Generally, dy1/dy2 != 0 for arbitrary functions y1 and y2. Is this reasoning correct?
 
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We can, however, talk about linearly-independent functions: namely, functions with vanishing Wronskian.
 
I can't figure out what the OP is saying about independent functions. It's not the same as the concept of linear independence, is it?
 
Ben Niehoff said:
We can, however, talk about linearly-independent functions: namely, functions with vanishing Wronskian.

It's when the Wronskian doesn't vanish that the two functions are linearly independent.
 
Heirot said:
When are to functions y1 = f1(x) and y2 = f2(x) independent? It would apper never, because, we can always write x = f1-1 (y1), and therefore y2 is a function of y1. Every function is dependent of any other function. Generally, dy1/dy2 != 0 for arbitrary functions y1 and y2. Is this reasoning correct?
I have no idea what you are saying! Do y1, y2, x1, x2 just represent numbers? What, then, is the difference between saying y1= f1(x1) and just y= f1(x)? And, of course, what do you mean by "independent"? Apparently you don't mean "linear independence". Before anyone can tell you whether or not "any two functions are not independent" you will have to say what you mean by two functions being "independent"!
 

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