Solution of polynomial equations

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Discussion Overview

The discussion revolves around the reformulation of a polynomial equation involving complex variables into a specific form involving two functions. Participants explore the conditions under which a polynomial equation of the form p(x_i, y_k) = 0 can be expressed as f(x_i) = g(y_k), with particular emphasis on the implications of the gradients of these functions.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant proposes a polynomial equation p(x_i, y_k) = 0 and questions whether it can be reformulated as f(x_i) = g(y_k) under certain conditions.
  • Another participant requests clarification on the polynomial constraint, indicating familiarity only with univariate polynomials.
  • A participant clarifies that the gradients mentioned imply that f does not depend on the y variables and g does not depend on the x variables.
  • There is a question about whether p(x_i, y_i) = 0 represents the product of univariate polynomials.
  • A participant asserts that p(x_i, y_k) is a general multivariate polynomial without special conditions.
  • One participant outlines a method involving differentiation of the polynomial and the proposed functions to derive conditions on the coefficients, suggesting that this could lead to proving the form of f and g.

Areas of Agreement / Disagreement

Participants express differing levels of familiarity with the polynomial constraints and the implications of the proposed reformulation. The discussion includes both exploratory reasoning and technical elaboration, with no consensus reached on the validity of the proposed approach or the nature of the polynomial.

Contextual Notes

Participants have not fully defined the polynomial constraints or the specific properties of the functions f and g. The discussion involves assumptions about differentiability and the nature of multivariate polynomials that remain unresolved.

tom.stoer
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Suppose there is a set of complex variables

[tex]\{x_i,\,i=1 \ldots M;\;\;y_k,\,k=1 \ldots N\}[/tex]

and a polynomial equation

[tex]p(x_i, y_k) = 0[/tex]

Is there a way to prove or disprove for such an equation whether it can be reformulated as

[tex]f(x_i) = g(y_k)[/tex]

with two functions f and g with

[tex]\nabla_y f= 0[/tex]
[tex]\nabla_x g= 0[/tex]
 
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Hey tom.stoer.

I'm not familiar with the polynomial constraint you use: can you point me to some more specific definition? (I'm sorry but I'm only familiar with a univariate polynomial).
 
You mean the gradient? It's only to stress that f does not depend on y1, y2, ... and g does not depend on x1, x2, ...
 
No sorry, I mean the p(x_i,y_i) = 0. Is this basically the product of univariate polynomials that is equal to 0?
 
No, its a general multivariate polynomial in xi and yi, no special construction, no special condition.
 
The intuition says its right, but we'll go through the formalities.

So you p(x_i,y_i) = 0 and f(xi) - g(y_j) = 0.

Now p(x_i,y_j) = f(xi) - g(yj) = 0.

You apply each individual operator once (with respect to the y's and x's respectively) and you'll get a cancellation on the RHS, but you will also get a condition on the LHS.

The LHS can be written as an expansion with all possible permutations of the x's and y's to various integer powers, and you should write the p(xi,yi) in this form with the coeffecients being variables.

When you do the differentiation on the LHS against both x and y, you should end up with a criteria for the coeffecients and which ones should be zero.

Be using both these differentiability constraints, you can prove the form of f and g since you will get a cancellation of the other when doing the derivative and then you're done.
 

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