Why a PDE is an infinite dimensional system

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    Infinite Pde System
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Discussion Overview

The discussion revolves around understanding the relationship between partial differential equations (PDEs) and infinite dimensional systems, particularly in the context of control of distributed parameter systems. Participants explore the nature of solutions to PDEs and their representation in mathematical frameworks such as Hilbert spaces and semigroups theory.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Homework-related

Main Points Raised

  • One participant notes that the solution to an ordinary differential equation can be expressed as a linear combination of independent solutions with a finite number of undetermined constants, suggesting a finite dimensional vector space.
  • Another participant contrasts this by stating that the solution to a partial differential equation involves a linear combination of independent solutions with undetermined functions, implying an infinite dimensional vector space.
  • A participant requests additional context about the original inquiry to provide better assistance.
  • The original poster explains their interest in the control of distributed parameter systems modeled by PDEs and their confusion regarding the transformation of PDEs into state space representations using linear operators and semigroups theory.

Areas of Agreement / Disagreement

Participants have not reached a consensus on the relationship between PDEs and infinite dimensional systems, and the discussion includes varying perspectives on the nature of solutions and their implications.

Contextual Notes

The discussion highlights the complexity of linking PDEs to semigroups analysis and the potential challenges faced by beginners in the subject, particularly regarding the mathematical frameworks involved.

zhidayat
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Hi,

I hope I posted in the right group. I read some papers about infinite dimensional systems and gave PDEs as examples of infinite dimensional systems. So far, I still cannot get why is that so.

Could everybody here help me giving relation between a PDE and an infinite dimensional system?

Thank you.
 
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The solution to an ordinary differential equation, of order n, can be written as a linear combination of n independent solutions, with n undetermined constants- a vector space of dimension n.

The solution to a partial differential equation, of order n, can be written as a linear combination of n independent solutions but with n undetermined functions. The functions themselves constitute an infinite dimensional vector space.
 
Thank you ... :)
 
Maybe if you told us the context--or the actual source--we may be better
able to help you.
 
the context is about control of distributed parameter systems which are modeled as PDEs. in papers i read (and try to understand), authors of the papers wrote the PDE and transform it into a state space representation using linear operator in Hilbert space and did the analysis using semigroups theory. since i am a beginner in the subject, i lost the link between the PDE and the semigroups analysis presented in the paper.

I would be grateful if i can get additional information.
 

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