Axioms of a Vector Space

Motivating the Eight Axioms

  • As a reminder, a vector can be any set of crazy object as long as there is a reasonable notion of adding and scaling
  • Take a moment to imagine yourself as a mathematician developing the theory of linear algebra
  • You want all of the definitions and discoveries of your work, such as linear transformations, determinants, etc, to apply to all of the vector-ish things (i.e. arrows, lists of numbers, etc.)
  • More specifically, you want all of the definitions and discoveries to apply to all of the vector-ish things in full generality, not just to one specific case
  • These sets of vector-ish things, like arrows or lists of numbers or functions, are called vector spaces
  • In other words, you'd want to establish a list of general rules (involving vector addition and scalar multiplication) that would need to be followed in order to apply all of the wonderful things about linear algebra (i.e. determinants, linear transformations, etc.) to your vector space
  • There are eight of these rules, and they are called axioms

The Eight Axioms of a Vector Space

  1. u+(v+w)=(u+v)+wu + (v + w) = (u + v) + w

    • Where u,v,u, v, and ww are any vector within the vector space
  2. v+w=w+vv + w = w + v

    • Where vv and ww are any vector within the vector space
  3. There is a zero vector 00 such that 0+v=v0 + v = v for all vv

    • Where vv is any vector within the vector space
    • Where 00 is the zero vector of the vector space
  4. For every vector vv, there is a vector v-v such that v+(v)=0v + (-v) = 0

    • Where vv is any vector within the vector space
    • Where 00 is the zero vector of the vector space
  5. a(bv)=(ab)va(bv) = (ab)v

    • Where vv is any vector within the vector space
    • Where aa and bb are any real numbers
  6. 1v=v1v = v

    • Where 11 is the real number 11
    • Where vv is any vector within the vector space
  7. a(v+w)=av+awa(v+w) = av + aw

    • Where aa is any real numbers
    • Where vv and w are any vector within the vector space
  8. (a+b)v=av+bv(a+b)v = av + bv

    • Where aa and bb are any real numbers
    • Where vv is any vector within the vector space

References

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