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Linear Independence

Let S = \{v_1, v_2, \ldots, v_n\} be a set of vectors in a vector space V.

Linear Independence

Let \(S = \{v_1, v_2, \ldots, v_n\}\) be a set of vectors in a vector space \(V\). If there exist scalars \(\alpha_1, \alpha_2 \ldots \alpha_n \in F\) such that not all of the \(\alpha_i\)'s are zero and \[\begin{aligned}\end{aligned}\], then \(S\) is said to be linearly dependent. If the set \(S\) is not linearly dependent, then it is said to be linearly independent. More specifically, \(S\) is a linearly independent set if \[\begin{aligned}\end{aligned}\] implies that \[\begin{aligned}\end{aligned}\] for any set of scalars \(\{ \alpha_1, \alpha_2 \ldots \alpha_n \}\).

The definition of linear dependence makes more sense if we consider the following proposition.

The following proposition is a consequence of the fact that any system of homogeneous linear equations with more unknowns than equations will have a nontrivial solution. We leave the details of the proof for the end-of-chapter exercises.

A set \(\{ e_1, e_2, \ldots, e_n \}\) of vectors in a vector space \(V\) is called a basis for \(V\) if \(\{ e_1, e_2, \ldots, e_n \}\) is a linearly independent set that spans \(V\).

Condensed: the full section is in Judson, Abstract Algebra: Theory and Applications.

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Questions people ask

What is a group, in plain words?

A set with one operation that is associative, has an identity, and lets every element be undone. Symmetries of any object form a group. That is where the idea came from.

What is the difference between a ring and a field?

A ring has addition and multiplication that behave like the integers (you cannot always divide); a field is a ring where every non-zero element has a reciprocal, like the rationals or the reals.

Parts of this page are adapted from Judson, Abstract Algebra: Theory and Applications (GFDL 1.3). Condensed and re-explained here; errors are ours.

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