How Is the Primary Decomposition Theorem Known in Various Mathematical Texts?

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Discussion Overview

The discussion revolves around the Primary Decomposition Theorem in linear algebra, specifically its formulation and the various names it may be known by in different mathematical texts. Participants explore the theorem's implications and seek clarification on its presentation in literature.

Discussion Character

  • Technical explanation, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant presents the theorem's statement involving the minimal polynomial and the existence of T-invariant subspaces.
  • Another participant references their own linear algebra notes as a source for the proof of the theorem, emphasizing the use of the linear combination property for polynomials with a gcd of 1.
  • There is a question regarding the correctness of the decomposition of the identity map and the corresponding subspaces.
  • A later reply expresses gratitude for the clarification provided, indicating some level of understanding achieved.
  • Another participant expresses a willingness to assist, suggesting a collaborative atmosphere in the discussion.

Areas of Agreement / Disagreement

Participants generally agree on the formulation of the theorem and its implications, but there is uncertainty regarding its naming and presence in various texts. The discussion does not resolve the question of alternative names for the theorem.

Contextual Notes

Limitations include the lack of consensus on the theorem's nomenclature and the potential dependence on specific definitions or contexts in which the theorem is presented.

Who May Find This Useful

Readers interested in linear algebra, particularly those studying the Primary Decomposition Theorem and its applications in vector spaces.

Treadstone 71
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"Let [tex]m(x)[/tex] be the minimal polynomial of [tex]T:V\rightarrow V, \dim V<\infty[/tex] such that [tex]m(x)=m_1(x)m_2(x)[/tex] where [tex]gcd(m_1,m_2)=1[/tex], then there exists [tex]T[/tex]-invariant subspaces [tex]V_1, V_2[/tex] such that [tex]V=V_1\oplus V_2[/tex]."

What other names is this thoerem called? It was given to me as the "primary decomposition theorem" but it's neither in my book nor in mathworld or wikipedia.
 
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look on my webpage, http://www.math.uga.edu/~roy/ and download my linear algebra notes. this is proved there.

the proof is based on the linear combination proeprty for gcd's, i.e. you can write 1 as a linear combination of two polynbomilas with gcd = 1, so if 1 = pm1 + qm2, then plugging in T for X, we get id = p(T)m1q(T) +q(T)m2(T). so we have decomposed the identity map into two direct sum components. this decompsoes V accordingly. i.e. V1 = ker pm1, and V2 = ker qm2. is that right? (i am a little under the weather at the moment.)
 
Yup, this is it. Thanks.
 
my pleasure. we live in the hope of being of service, and occsionally this occurs.
 

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