Positive polynomial in two real variables

In summary, the conversation discusses the possibility of a continuous function not attaining its lower bound and how that could relate to positive polynomials in two real variables. The possibility is considered through the use of Sylvester's theorem, which suggests that positive defined polynomials never reach the plane. The approach is to examine the properties of a continuous function that does not attain its lower bound and prove that a polynomial cannot have those properties. However, there is some uncertainty about how Sylvester's theorem would be used in this scenario.
  • #1
gvk
83
0
Does every positive polynomial in two real variables attain its lower bound in the plane? :yuck:
 
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  • #2
Let's start by investigating how it could fail.


Do you know of any way that a continuous function can fail to attain its lower bound?
 
  • #3
Hurkyl said:
Let's start by investigating how it could fail.

Do you know of any way that a continuous function can fail to attain its lower bound?
Do you mean the function which asymptoticaly aproaches the plane when x ->infinity?
It seems to me that, according the Sylvester's theorem the positive defined polynomial never reaches the plane, and it does not matter how behave the continuous function.
 
  • #4
I was suggesting a possible line of attack: examime what properties a continuous function must have if it doesn't attain its lower bound, then prove a polynomial can't have those polynomials.


But it sounds like you already have a line of attack... how are you proposing to use Sylvester's theorem?

(I don't recall the theorem; a quick google search doesn't provide anything that seems relevant)
 

What is a positive polynomial in two real variables?

A positive polynomial in two real variables is a polynomial expression with two variables (usually represented by x and y) that has only positive coefficients. This means that all the numbers in the polynomial are greater than zero.

What is the degree of a positive polynomial in two real variables?

The degree of a positive polynomial in two real variables is the highest power of the variables in the expression. For example, in the polynomial 3x^2 + 5xy + 2y^3, the degree is 3 because the highest power of any variable is 3.

What is the difference between a positive polynomial and a non-positive polynomial?

A positive polynomial has only positive coefficients, while a non-positive polynomial can have both positive and negative coefficients. In other words, a positive polynomial will always result in a positive value when the variables are substituted, while a non-positive polynomial may result in a negative value.

Can a positive polynomial have negative exponents?

No, a positive polynomial cannot have negative exponents. This is because a negative exponent would result in a fraction, and fractions cannot be considered positive. Therefore, all exponents in a positive polynomial must be zero or positive.

How can positive polynomials be used in real-world applications?

Positive polynomials are commonly used in optimization problems, where the goal is to find the maximum or minimum value of a function. They can also be used in economics, physics, and other fields to model relationships between variables and make predictions. Additionally, positive polynomials have applications in computer science, such as in graph theory and computer graphics.

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