Understanding $\mathbb{K}$ and $\mathbb{R}^n$ - Get Your Answers Here

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Discussion Overview

The discussion revolves around the meanings and implications of the symbols $\mathbb{K}$ and $\mathbb{R}^n$ in mathematical contexts. Participants explore the definitions and assumptions associated with these symbols, particularly in relation to fields and vector spaces.

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants propose that $\mathbb{K}$ typically refers to an arbitrary field, but emphasize that its specific meaning should be clarified in context.
  • Others clarify that $\mathbb{R}^n$ denotes n-dimensional real space, which can be understood as a unique n-dimensional vector space over the real numbers.
  • A later reply introduces a distinction, noting that $\mathbb{R}^n$ can be viewed as the set of ordered n-tuples of real numbers, and that it becomes a vector space only when specific operations like "sum" and "scalar multiplication" are defined coordinate-wise.
  • Another participant acknowledges the previous points but suggests that in most literature, the vector space structure and associated properties are often assumed when referring to $\mathbb{R}^n$.
  • There is a suggestion to be cautious about assumptions regarding algebraic structures when interpreting these symbols.

Areas of Agreement / Disagreement

Participants express some agreement on the general meanings of $\mathbb{K}$ and $\mathbb{R}^n$, but there is disagreement regarding the implications and assumptions that should accompany these definitions, particularly concerning the vector space structure of $\mathbb{R}^n$.

Contextual Notes

Participants note that the definitions of $\mathbb{K}$ and $\mathbb{R}^n$ may depend on the context in which they are used, and that assumptions about vector space structures or algebraic properties may not always be explicitly stated.

Hernaner28
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Hi. What does that mean when we see:

$$\mathbb{K}$$ what set is that? definitely not the reals, integers, etc.
and
$$\mathbb{R}^n$$ Is that the reals or what?

Thanks!
 
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the blackboard K is often used to refer to an arbitrary field. If you encounter it somewhere it should be stated what is meant by it.

The blackboard R^n just means n-dimensional real space. So basically (up to linear isomorphism) the unique n-dimensional vector space over the real numbers.
 
Thank you!
 
conquest said:
the blackboard K is often used to refer to an arbitrary field. If you encounter it somewhere it should be stated what is meant by it.

The blackboard R^n just means n-dimensional real space. So basically (up to linear isomorphism) the unique n-dimensional vector space over the real numbers.
A tiny disagreement. R^n is the set of order n-tuples of real numbers. It becomes a vector space only with the convention that "sum" and "scalar multiplication" are "coordinate wise". Yes, that is the "natural" convention but it separate from just "R^n".
 
You are right of course. Naturally my response was in terms of the vector space since this is the first definition I saw. You could also assume this and express that you are only talking strictly as the n-tuples of real numbers by mentioning you use the bare set underlying the vector space. I think in most literature the vector space (indeed also the natural topological, norm, inner product, Lie group and manifold (symplectic, smooth, Riemannian)) structure are assumed when used. A thing that might be stated explicitely is any algebra structure.

So immediately when I see that symbol these things I also assume, but it might pay to be a bit more reserved about this.
 

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