What is the principal representation?

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Discussion Overview

The discussion revolves around the concept of the principal representation in representation theory. Participants seek clarity on its definition and context, exploring its relationship to other terms such as trivial representation.

Discussion Character

  • Exploratory, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant asks for a clear definition of the principal representation, noting difficulty in finding it in literature.
  • Another suggests that it may refer to the natural representation of an object acting on itself through multiplication.
  • A participant cites Isaacs, indicating that characters of degree 1 are called linear characters, and mentions that the function 1G is referred to as the principal F-character.
  • There is a question about whether this definition aligns with the trivial representation.
  • One participant expresses confusion about the terminology, questioning why it is not simply called the trivial representation.
  • A later reply speculates that historical naming conventions may explain the terminology differences and notes that terms can have multiple meanings.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the definition of principal representation, and there are competing views regarding its terminology and relationship to trivial representation.

Contextual Notes

There are unresolved questions regarding the historical context of the terminology and the potential for multiple meanings associated with the term principal representation.

Ultraworld
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Question on representation theory. What is the principal representation? I would like a good clear definition. I can't find it in my book (bad index) nor can I find it on the web.
 
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It could be one of many things. Probably it is the natural representation of whatever kind of object you care about acting on itself by left (or right) multiplication. Where did you come across the phrase if it isn't defined anywhere?
 
Isaacs: "Characters of degree 1 are called linear characters. In particular, the function 1G with constant value 1 on G is a linear F-character. Is is called the principal F-character"

I want to know what a principal representation is.
 
In what way is that not the definition of the principal (aka trivial) representation?
 
I have no idea. Perhaps when Isaacs wrote his book (a long time ago), that was what they called it. It also has links with the principal block too. Some times things have two names. Some times one name has two meanings. That's just the way it crumbles cookie wise.
 

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