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Standard Basis

Last updated Nov 1, 2022

# Definition

Let FF be a Field

Field

Definition Suppose XX is a , and +:X×XX+: X \times X \to X, :X×XX: X \times X \to X are...

11/7/2022

and let nNn \in \mathbb{N}. Denote ϵi=(0,,0,1,0,,0)Fn\epsilon_{i} = (0, \dots, 0, 1, 0, \dots, 0) \in F^{n} to be the element of all 00’s except for a 11 in the iith position for some i[n]i \in [n]. The Standard Basis

Standard Basis

Definition Let FF be a and let nNn \in \mathbb{N}. Denote $\epsilon_{i} = (0, \dots, 0, 1, 0, \dots, 0)...

11/7/2022

is the set: S=ϵii=1nS = {\epsilon_{i}}_{i=1}^{n}

# Remarks

# The Standard Basis

Standard Basis

Definition Let FF be a and let nNn \in \mathbb{N}. Denote $\epsilon_{i} = (0, \dots, 0, 1, 0, \dots, 0)...

11/7/2022

is a Vector Space Basis

Vector Space Basis

Definition Let VV be a . Then SVS \subset V is a basi for VV if spanS=V\text{span} S = V SS is...

11/7/2022

for FnF^{n}

SS spans

Subspace Span

Definition Let VV be a on FF. Let SVS \subset V. The of SS is $$\text{span} S =...

11/7/2022

FnF^{n}: for any x=(x1,,xn)Fn\mathbf{x} = (x_{1}, \dots, x_{n}) \in F^{n}, we have that x1ϵ1++xnϵn=x.x_{1} \epsilon_{1} + \cdots + x_{n} \epsilon_{n} = \mathbf{x}. The Subspace Span is the Set of all Linear Combinations

The Subspace Span is the Set of all Linear Combinations

Statement Let VV be a on FF. Let SVS \subset V. Then $$\{c{1} \mathbf{x}{1} + \cdots + c{n} \mathbf{x}{n} \in...

11/7/2022

, so spanSFn\text{span} S \supset F^{n}. But, spanSFn\text{span} S \subset F^{n} by definition, so we must have that spanS=Fn\text{span} S = F^{n}. \checkmark

SS is Linearly Independent

Linearly Independent

Definition 1 Let VV be a on FF. Let SVS \subset V. SS is if it is not...

11/7/2022

: Suppose c1,,cnFc_{1}, \dots, c_{n} \in F and that c1ϵ1++cnϵn=0.c_{1} \epsilon_{1} + \cdots + c_{n} \epsilon_{n} = \mathbf{0}. But c1ϵ1++cnϵn=(c1,,cn)=0=(0,,0),c_{1} \epsilon_{1} + \cdots + c_{n} \epsilon_{n} = (c_{1}, \dots, c_{n}) = \mathbf{0} = (0, \dots, 0), so c1==cn=0c_{1} = \cdots = c_{n} = 0, and we have that SS is Linearly Independent

Linearly Independent

Definition 1 Let VV be a on FF. Let SVS \subset V. SS is if it is not...

11/7/2022

. \checkmark \blacksquare