Question | Answer |
Vector Space | A vector space V over a field F, is an Abelian group under addition and closed over scalar multiplication.
The elements of F are called SCALARS
The elements of V are called VECTORS |
Examples of Vector Spaces | R^n is a vector space over R
M(2x2) is a vector space over R
C is a vector space over R |
Basis for V | A BASIS for V is a set of vectors that are linearly independent and span V. |
linearly independent | v1,v2,...,vn are linearly independent if the only solution to c1v1+c2v2+...+cnvn=0, is ci=0 |
span | v1,v2,...,vn SPAN V if for all v in V there exists ci such that c1v1+c2v2+...+cnvn=v |
A basis is a... | minimal spanning set |
A basis is a..... | maximal linearly independent set |
Theorem about Vector spaces and Bases | Every vector space has a basis
Proof: Zorn's Lemma |
Vector Space letters | For all v in V, a in F, av in V,
1) a(v+w)=av+aw
2)(a+b)v=av+bv
3)(ab)v=a(bv)
4)1*v=v |
Subspace | U is a SUBSPACE of V if U is a subset that is also a vector space over F. |
Subspace spanned | Let v1,v2,...,vn be in V, then <v1,v2,...,vn>={a1v1+a2v2+...+anvn|ai is in F} is called a subspace spanned by v1,v2,...vn. |
Linear combination | a1v1+a2v2+...+anvn is called a linear combination of v1,v2,...,vn if V=<v1,v2,...,vn>, then {v1,v2,...vn} spans V.
{v1,v2,...,vn} is a spanning set for V. |
Linearly independent | v1,v2,...,vn are LINEARLY INDEPENDENT over F if there exists a1,a2,...,an in F (not all 0) such that a1v1+a2v2+...+anvn=0 |