Algebraic Multiplicity of an Eigenvalue

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SUMMARY

The algebraic multiplicity of an eigenvalue λ is defined as the multiplicity of λ in the factorization of the characteristic polynomial A - cI. In contrast, the geometric multiplicity is represented by dim null [T - λ I]. The discussion highlights the confusion between these two concepts, emphasizing that they may not coincide. The user seeks assistance in completing a proof related to the algebraic multiplicity, specifically referencing an ebook for further clarification on the definitions and relationships between these multiplicities.

PREREQUISITES
  • Understanding of eigenvalues and eigenvectors in linear algebra
  • Familiarity with the concepts of algebraic and geometric multiplicity
  • Knowledge of matrix factorization and characteristic polynomials
  • Experience with null spaces and linear transformations
NEXT STEPS
  • Study the relationship between algebraic and geometric multiplicity in linear transformations
  • Review the proof techniques for eigenvalue multiplicity in linear algebra
  • Examine the characteristic polynomial and its role in determining eigenvalues
  • Explore the implications of upper triangular matrices on eigenvalue multiplicities
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Students and professionals in mathematics, particularly those studying linear algebra, as well as educators seeking to clarify the concepts of eigenvalue multiplicities.

vish_maths
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Please have a look at the attached images.I am attempting a proof for the statement : The algebraic multiplicity of an eigen value λ is equal to dim null [T - λ I] dim V.

Please advise me on how to move ahead. Apparently, I am at the final inference required for a proof but unable to move ahead. Thank you very much for your help in this regard.

Reference : To know how results (2) and (3) in the images come, you may please have a look at this ebook - pg 165, http://fetweb.ju.edu.jo/staff/EE/jrahhal/PDF/sc%20-%20Linear%20Algebra%20Done%20Right.pdf
 

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In my experience, the definition you gave is of the _geometric _ multiplicity, not the algebraic one. The two multiplicities may or may not coincide.
 
WWGD said:
In my experience, the definition you gave is of the _geometric _ multiplicity, not the algebraic one. The two multiplicities may or may not coincide.
Thank you for the answer. The notes which I have say that the number of times λ appears on the diagonal of an upper triangular matrix is equal to dim null [T - λ I] dim V. Do you think there is error in this statement as well?"

I have actually attempted the proof to prove this statement. Sorry about incorrectly saying it equal to algebraic multiplicity
 
Ah, sorry, I did not see the exponent dimV in your post , at first. In my experience, the geometric multiplicity of ## \lambda ## is the dimension of null## [T- \lambda I] ##. The algebraic multiplicity of ## \lambda ## is the multiplicity of the exponent of ##\lambda## in the factorization of ## A-cI ##.
 
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No problem :) . Do you think I made a good attempt at the proof? I just think i got stuck in the last stage of the proof
 

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