Linear Transformation (Fredholm Alternative Theorem)

In summary, a linear transformation is a mathematical operation that maps one vector space to another in a linear manner, often represented by a matrix. The Fredholm Alternative Theorem is a fundamental theorem in linear algebra that provides a condition for the existence and uniqueness of solutions to linear equations. It is used to analyze and solve equations in various scientific fields, and has applications in optimization and differential equations. The significance of the theorem lies in its ability to provide a powerful tool for understanding linear systems. However, it cannot be extended to non-linear systems, for which other theorems and techniques must be used.
  • #1
Swati
16
0
Let T:V->V be a linear operator on an n-dimensional vector space. Prove that exactly one of the following statements holds:

(i) the equation T(x)=b has a solution for all vectors b in V.

(ii) Nullity of T>0
 
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  • #2
Swati said:
Let T:V->V be a linear operator on an n-dimensional vector space. Prove that exactly one of the following statements holds:

(i) the equation T(x)=b has a solution for all vectors b in V.

(ii) Nullity of T>0

Hi Swati, :)

Suppose that the first statement is true. That is \(T\) is surjective. Then,

\[\mbox{dim }(V)=\mbox{dim }(\mbox{Im }T)=n\]

Then by the Rank-Nullity Theorem,

\[\mbox{Nullity }T=\mbox{dim }(\mbox{Ker }T)=0\]

Conversely you can show that if the second statement is true the first statement cannot be true.

Kind Regards,
Sudharaka.
 
  • #3
how to proof if second statement is true then first statement is false.
 
  • #4
Swati said:
how to proof if second statement is true then first statement is false.
Use the rank-nullity theorem again, to show that T is surjective.
 
  • #5
if the SECOND statement is true, T CANNOT be surjective:

by the rank-nullity theorem:

dim(V) = rank(T) + nullity(T).

if nullity(T) > 0, then rank(T) < dim(V), so that:

dim(im(T)) < dim(V).

thus there is some b in V not in im(T).

(i only posted this because Opalg's post answers the wrong question).
 
  • #6
Deveno said:
if the SECOND statement is true, T CANNOT be surjective:

by the rank-nullity theorem:

dim(V) = rank(T) + nullity(T).

if nullity(T) > 0, then rank(T) < dim(V), so that:

dim(im(T)) < dim(V).

thus there is some b in V not in im(T).

(i only posted this because Opalg's post answers the wrong question).
Yes of course. I should have said: Use the rank-nullity theorem again, to show that T is NOT surjective.
 

FAQ: Linear Transformation (Fredholm Alternative Theorem)

What is a linear transformation?

A linear transformation is a mathematical operation that maps one vector space to another in a linear manner. It is often represented by a matrix and can be used to describe various physical phenomena in science, such as the motion of particles or the flow of fluids.

What is the Fredholm Alternative Theorem?

The Fredholm Alternative Theorem is a fundamental theorem in linear algebra that provides a condition for the existence and uniqueness of solutions to linear equations. It states that either the equation has a unique solution or the associated homogeneous equation has a non-trivial solution.

How is the Fredholm Alternative Theorem used in science?

In science, the Fredholm Alternative Theorem is used to analyze and solve linear equations that arise in various fields, such as physics, engineering, and economics. It is also used in optimization problems and in the study of differential equations.

What is the significance of the Fredholm Alternative Theorem?

The Fredholm Alternative Theorem is significant because it provides a powerful tool for solving linear equations and understanding the behavior of linear systems. It also has applications in many areas of science and engineering, making it an important concept for scientists to understand.

Can the Fredholm Alternative Theorem be extended to non-linear systems?

No, the Fredholm Alternative Theorem only applies to linear systems. However, there are other theorems and techniques that can be used to analyze and solve non-linear systems, such as the Banach Fixed Point Theorem and the Newton-Raphson method.

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