Defining Direct Products in Exponents

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Discussion Overview

The discussion revolves around the definition of direct products when used in the exponent of a variable, exploring various interpretations and notations associated with this concept. The scope includes theoretical aspects and mathematical reasoning related to tensor products and expansions.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants propose that the direct product in the exponent can be defined via a Taylor expansion.
  • Others suggest that the notation G^{\otimes} might represent the tensor product of multiple instances of G, specifically G \otimes G \otimes G \otimes ...
  • One participant mentions that t could also be defined by an eigenfunction expansion.
  • There is a request for clarity and precision regarding the notation and its meaning, indicating some confusion among participants.
  • Another participant refers to standard notation \overset{k}{\otimes}V, which denotes the tensor product of V repeated k times.
  • A link to an external source is provided for further reference regarding the notation.
  • It is noted that the tensor product of N copies of rho is relevant to the discussion.

Areas of Agreement / Disagreement

Participants express uncertainty and confusion regarding the definitions and notations, indicating that multiple competing views remain without a consensus on the precise meaning of the direct product in the exponent.

Contextual Notes

There are limitations in clarity regarding the definitions and notations used, as well as unresolved questions about the context in which these terms are applied.

Nusc
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When the direct product is in the exponent of some variable, how is it defined?
 
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I would say that it's defined via the Taylor expansion. Can you give the explicit expression?
 
Like O(3) ^ direct product blah
 
You mean something like

[itex] <br /> G^{\otimes}<br /> [/itex]
? I never saw such a thing, but I would then guess it's a notation for

[itex] G \otimes G \otimes G \otimes \ldots \otimes G[/itex]

Does that make sense in your context? Otherwise you should give the exact expression in LaTeX :)
 
t is defined either by a Taylor expansion or by an eigenfunction expansion.
 
Nusc said:
When the direct product is in the exponent of some variable, how is it defined?

There seems to be confusion in this thread (at least for me).

Please write down clearly, completely, and precisely what you mean, or give a reference to a text or paper which uses the notation that you want want clarified.
 
haushofer said:
You mean something like

[itex] <br /> G^{\otimes}<br /> [/itex]

Something like that. What does it mean?
 
Last edited by a moderator:
Nusc said:
Something like that. What does it mean?

Do you mean "something like" or "exactly like"? You have to be precise.

Do you mean

[tex]\overset{k}{\otimes}V?[/tex]

This is standard notation for

[tex]V \otimes V \otimes \ldots \otimes V[/tex]

with [itex]V[/itex] repeated [itex]k[/itex] times.
 
  • #10
It's the tensor product of N copies of rho.
 
  • #11
thanks
 

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