Linear Dependence

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linear dependence

[′lin·ē·ər di′pen·dəns]
The property of a set of vectorsv, …,vn in a vector space for which there exists a linear combination such that a1v1+ ··· + an vn = 0, and at least one of the scalars ai is not zero.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Linear Dependence


(mathematics), a relationship of the form

(*) C1u1 + C2u2 + ... + Cnun = 0

where C1, C2,..., Cn are numbers, at least one of which is not zero, and u1, u2,..., un are various mathematical objects for which the operations of addition and multiplication by a number are defined. The dependence relation (*) is said to be linear in the objects u1, u2,..., un, since each of them enters (*) linearly, that is, the degree of each ui in (*) is one. The equality sign in the above relation may have various meanings and its sense must be specified in each particular case.

The concept of linear dependence is used in many branches of mathematics. We may thus speak, for example, of linear dependence between vectors, between functions of one or several variables, and between elements of a vector space. If the objects u1, u2,..., un are connected by a relation of linear dependence, then we say that they are linearly dependent. In the opposite case we say that they are linearly independent. If the objects u1, u2,..., un are linearly dependent, then at least one of them is a linear combination of the others, that is,

ui = α1u1 + ... + αi - 1ui-1 + αi + 1ui + 1 + ... + αnun

Continuous functions of one variable

u1 = ϕ1(x), u2 = ϕ2(x), . . ., un = ϕn (x)

are said to be linearly dependent if they are connected by a relation of the form (*), in which the equality sign is understood as an identity in x. In order for the functions Φ1(x), Φ2(x), . . ., Φn(x) defined on an interval axb to be linearly dependent, it is necessary and sufficient that their Gramian vanish, the Gramian in this case being the determinant


However, if the functions Φ1(x), Φ2(x),..., Φn(x) are solutions of a linear differential equation, then they are linearly dependent if and only if their Wronskian vanishes at at least one point.

Linear forms in M variables

ui = ai 1x1 + ai 2x2 + ... + aimxmi = 1, 2,..., n

are said to be linearly dependent if they are connected by a relation of the form (*), in which the equality sign is understood as an identity in all the variables x1, x2,..., xm. In order for n linear forms in n variables to be linearly dependent, it is necessary and sufficient that the following determinant vanish:

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
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