Vector space Definition and 540 Threads

A vector space (also called a linear space) is a set of objects called vectors, which may be added together and multiplied ("scaled") by numbers, called scalars. Scalars are often taken to be real numbers, but there are also vector spaces with scalar multiplication by complex numbers, rational numbers, or generally any field. The operations of vector addition and scalar multiplication must satisfy certain requirements, called vector axioms (listed below in § Definition). To specify that the scalars are real or complex numbers, the terms real vector space and complex vector space are often used.
Certain sets of Euclidean vectors are common examples of a vector space. They represent physical quantities such as forces, where any two forces (of the same type) can be added to yield a third, and the multiplication of a force vector by a real multiplier is another force vector. In the same way (but in a more geometric sense), vectors representing displacements in the plane or three-dimensional space also form vector spaces. Vectors in vector spaces do not necessarily have to be arrow-like objects as they appear in the mentioned examples: vectors are regarded as abstract mathematical objects with particular properties, which in some cases can be visualized as arrows.
Vector spaces are the subject of linear algebra and are well characterized by their dimension, which, roughly speaking, specifies the number of independent directions in the space. Infinite-dimensional vector spaces arise naturally in mathematical analysis as function spaces, whose vectors are functions. These vector spaces are generally endowed with some additional structure such as a topology, which allows the consideration of issues of proximity and continuity. Among these topologies, those that are defined by a norm or inner product are more commonly used (being equipped with a notion of distance between two vectors). This is particularly the case of Banach spaces and Hilbert spaces, which are fundamental in mathematical analysis.
Historically, the first ideas leading to vector spaces can be traced back as far as the 17th century's analytic geometry, matrices, systems of linear equations and Euclidean vectors. The modern, more abstract treatment, first formulated by Giuseppe Peano in 1888, encompasses more general objects than Euclidean space, but much of the theory can be seen as an extension of classical geometric ideas like lines, planes and their higher-dimensional analogs.
Today, vector spaces are applied throughout mathematics, science and engineering. They are the appropriate linear-algebraic notion to deal with systems of linear equations. They offer a framework for Fourier expansion, which is employed in image compression routines, and they provide an environment that can be used for solution techniques for partial differential equations. Furthermore, vector spaces furnish an abstract, coordinate-free way of dealing with geometrical and physical objects such as tensors. This in turn allows the examination of local properties of manifolds by linearization techniques. Vector spaces may be generalized in several ways, leading to more advanced notions in geometry and abstract algebra.
This article deals mainly with finite-dimensional vector spaces. However, many of the principles are also valid for infinite-dimensional vector spaces.

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  1. S

    Vector Space, (not calc i guess)

    We're working on vector spaces right now and this one problem is iving me a bit of trouble. Is the following a vector space? The set of all polynomials of the form n_2x^2 + n_1x + n_0 where n_0,n_1,n_2 \epsilon Z (integers)Now I'm pretty sure that this is going to end up NOT being a vector...
  2. R

    Tangent Vector Spaces: Clarifying Dimension and Interpretation

    I see in my notes (I don't carry The Encyclopedia Britannica around with me) that George Mostow, in his artical on analytic topology, says "The set of all tangent vectors at m of a k-dimensional manifold constitutes a linear or vector space of which k is the dimension (k real)." Well ok, maybe...
  3. I

    Verifying Vector Space Properties of $\mathbb{R}^2$

    let \mathbb{R}^2 be a set containing all possible columns: \left( \begin{array}{cc} a \\ b \right) where a, b are arbitrary real numbers. show under scalar multiplication and vector addition \mathbb{R}^2 is indeed a vector space over the real number field. I will check the eight...
  4. A

    Proving F^\int as an Infinite Vector Space

    How could I proof that F^\int is infinite vector space?
  5. X

    Prove vector space postulate 1.X = X is independent of others

    Hi everyone, I would like to seek help in proving that the vector space postulate 1.X = X cannot be derived from the other postulates, e.g. X + 0 = X, X + (Y + Z) = (X + Y) + Z. The only hint I am given is to construct the "pseudo-scalar product" c # X = the projection of c.X on a fixed...
  6. A

    Every vector space is the dual of some other vector space

    Can someone prove this to me? I know that if you have a finite dimensional vector space V with a dual space V*, then every ordered basis for V* is the dual basis for some basis for V (this follows from a theorem). But if you're just given an arbitrary vector space V. Let's say the Space of R^n...
  7. C

    Are solultions of D.E. a Vector Space?

    ---------------------- Let V be the solutions to the differential equation: a_{1}y' + a_{0} = x^2 + e^x Decide using the properties of pointwise addition and scalar multiplication if V is a vector space or not. --------------------- Ok I am having real trouble with this...
  8. A

    Proving Vector Space of All Real Numbers

    i know that the set "all real numbers" make up a vector space, but how do you prove that it is so?
  9. A

    Proving Vector Space of Positive Quadruples of Real Numbers

    how do you prove the set of vectors "all ordered quadruples of positive real numbers" make a vector space?
  10. M

    Proving the Validity of a Set of Vectors as a Basis for a Vector Space

    Hi Given a Vector Space V which has the basis \{ v_{1}, v_{2}, v_{3} \} then I need to prove that the following set v = \{ v_{1}, v_{1}+ v_{2}, v_{1} + v_{2} + v_{3} \} is also a basis for V. I know that in order for v to be a basis for V then V = span \{v_{1}, v_{1}+ v_{2}, v_{1} +...
  11. S

    Is a(x,y,z) = (2ax,2ay,2az) a Vector Space?

    decide whether this is a vector space or not a(x,y,z) = (2ax,2ay,2az) all the addition axoims hold easily for the scalar multiplications axioms for some real scaral a a(x,y,z) = (ax,ay,az) \in 2(ax,ay,az) a(x_{1}+x_{2},y_{1}+y_{2},z_{1}+z_{2}) = a(x_{1},y_{1},a(z_{1}) +...
  12. M

    Proving Triangle Inequality for L-Normed Vector Space

    Hi I'm given the following assignment which deals with to looks like an L-normed vectorspace: Prove that, |f(y_1) - f(y_2)| \leq || y_1 - y_2|| To prove this do I approach the above as a triangle inequality or as a cauchy-swartz inequality? Best Regards, Fred
  13. R

    Why do we need infinite dimensional vector spaces?

    We have x=x1(1,0,0) + x2(0,1,0) + x3(0,0,1) to represent R^3. That's a finite dimensional vector space. So what do we need infinite dimensional vector space for? Why do we need (1,0,0,...), (0,1,0,0,...), etc. bases vectors to represent R^1 ?
  14. R

    Linear Algebra: The vector space R and Rank

    Two m x n matrices A and B are called EQUIVALENT (writen A ~e B if there exist invertible matracies U and V (sizes m x m and n x n) such that A = UBV a) prove the following properties of equivalnce i) A ~e A for all m x n matracies A ii) If A ~e B, then B ~e A iii) A ~e B and B~e C, then...
  15. C

    V not vector space with degree 3 polynomials

    Okay, so i have this problem in my text, and I've almost figured it out (i think) but i need a little help "Let V be the set of all polynomials of degree 3. Define addition and scalar multiplication pointwise. Prove that V with respect to these operations of addiont and scalar multiplication...
  16. B

    Finite dimensional real vector space

    Hi can someone assist me with the following question? Q. Let V be a finite dimensional real vector space with inner product < , > and let W be a subspace of V. Then the orthogonal complement of W is defined as follows. W^o = \{ v \in V: < v,w > = 0,w \in W\} Prove the following...
  17. P

    Proving Vector Space Identity: I-T Bijectivity

    Hello, I am having trouble with particular algebra question. I don't know where to start and it would be greatly appreciated if someone could point me in the right direction. Here is the questoin: Let V be a vector space, where T is a linear map of V prove if T^2 = 0 then I - T is...
  18. C

    Can (x,y,z) be used to represent both a point and a vector?

    Hi everybody, I have one question about vectors of R^3: First of all, a point is described by its co-ordinates (x,y,z). A vector r is described in this way: r=ax+by+cz ,where {x,y,z} is the standard basis (the numbers a,b,c are the "coordinates" of the vector). But i have seen in several...
  19. R

    Describing Span of Set in P4 Vector Space

    Okay, so I am doing this homework question, and its bothering me, so i thought perphaps somebody can help me out. " Let P4 denote the vector space of all polynomials with degree less than or equal to 4 and real coefficients. Describe percisely as you can the linear span of set {x^2 – x^4...
  20. A

    Definition of the number of dimensions of a vector space

    I understand that the definition of the number of dimensions of a vector space, but somehow that doesn't really help me with physical dimensions. How in practice do we know that our space is 3-dimensional?
  21. R

    Vector Space & Vector Subspaces

    Hello... I've been doing some home work on Vector Spaces and Vector Subspaces and I need help solving a problem... Can somebody please help me? Consider the differential equation f'' + 5f' + 6f' = 0 Show that the set of all solutions of this equation is a vector subspace of the...
  22. G

    Vector Space Axioms which fail certain matrices

    Second week in Linear Algebra... My homework involves of identifying all failing Vector Space Axioms for various sets of vector spaces. I did fine with a "regular" set like (x,y,z) which has an operation like k(x,y,z)=(kx,y,z). I have worked through all 10 of the axioms, comparing left sides...
  23. L

    Is V Also a Vector Space Over the Real Numbers?

    Let V = {(a1, a2, ..., an): ai in C for i = 1, 2, ... n}; (C=complex numbers) ; so, V is a vector space over C. Is V a vector space over the field of real numbers with the operaions of coordinatewise addition and multiplication? I thought the answer to this question is No since after we...
  24. H

    Is the Empty Set a Valid Vector Space? A Closer Look at the Ten Axioms

    While reading text, I had a question which I can not resolve by myself. Please Help me! it reads, The empty set( a vector space with no elements) is denoted as & (This symbol doesn't matter for the sake of argument, I don't know how to write the Zero with a line in the middle). I can...
  25. R

    Exploring the Relationship Between Affine and Vector Spaces

    Hi what are the differences between affine and vector spaces ? Please can you give me examples. thanks roger
  26. P

    Vector Space Problem: Is {x1,x2,x3} a Vector Space?

    Is the following a vector space: the set of all ordered triples of real numbers, {x1,x2,x3)}, usual addition, and r(x1,x2,x3)=(0,0,0), all numbers r I think this is a vector space since it is the vector (0,0,0), but I'm not sure how to show the work for it. Thanks in adv.
  27. L

    Let V be a 5 dimensional vector space

    Let V be a 5 dimensional vector space, and let \Delta be a determinant formon V. Given \Delta(b1, b2, b3, b4, b5)= -3 How do I find \Delta(b4, b3, b5, b1, b2)?
  28. L

    Vector Space P_4: Basis with Tchebychev Polynomials

    In the vector space P_4 of all polynomials of degree less than or equal to 4 we define the first five Tchebychev polynomial as p_0(x) = 1 p_1(x) = x p_2(x) = 2x^2 - 1 p_3(x) = 4x^3 - 3x p_4(x) = 8x^4 - 8x^2 + 1 To show that B={p_0, p_1, p_2, p_3, p_4} is a basis of P_4, do I put them...
  29. S

    Equivilant norms of a Vector Space

    This is killing me that I can't see this. Why is it two norms on a finite dimensional Vector space X are equivilant if and only if there exist positive real constants c_1,\, c_2 such that \forall x\in X, \|x\|_2 \le c_1 \|x\|_1 and \|x\|_1 \le c_2 \|x\|_2. Here equivilant means that a...
  30. C

    Finding k for Linear Dependence in a Vector Space

    I would really appreciate if anyone could help me with this problems. V is a vector space on R and v1, v2, v3 e V are linearly independant. If w1 = v1 + kv2, w2= v2 - 2kv3 and w3= v3 - 4kv, find k so w1, w2, w3 are linearly dependant. I tried it and got k=0 and I think it's wrong :mad:
  31. E

    Is {1/n^x} an Element of l^p for Various Values of x and p?

    So if we let x>0, For which 0<p<=infinity is {1/n^x} an element of l^p? If x=1, then 1/n^x is clearly an element of l^p for p>=2, since for all these vector spaces, the series of 1/n will converge? But if x<1, then in it seems that only for p=infinity, will {1/n^x} be an element of l^p. Is...
  32. M

    Proving R^2 is a Vector Space: Finding Zero Vector & More

    I had this question in my book asking me to show these things in detail, but it seems easy yet i don't understand why teacher said it was a little difficult: 1) Prove that R^2(with the rules of addition and scalar multiplication) is a vector space and find (zero vector)? 2)Deduce from the...
  33. C

    Is Order of Operations the Same in Vector Spaces as in Junior High School?

    Hi everybody, In vector spaces we define two operations, addition and scalar multiplication. Scalar multiplication is distributive over addition. This can define the order of operations in the vector space? I mean when we have an expression to calculate, we know that we firstly calculate...
  34. E

    Vector Space Solutions for Systems: Explained Here

    Hi everyone, general question: is a solution set for a particular system a vector space? I know it can be if there is a unique solution, but is it generally true? Could someone explain, please? Thanks.
  35. A

    Can Matrix Dimensions Vary Within the Same Vector Space Transformation?

    If I have a finite dimensional inner product space V = M_{n \times n}(\mathbb{R}), then one basis of V is the set of n² (n x n)-matrices, \beta = \{E_1, \dots , E_{n^2}\} where E_i has a 1 in the i^{th} position, and zeroes elsewhere (and by i^{th} position, I mean that the first position is the...
  36. S

    Exploring Spanning Sets: Can I Understand This Vector Space Problem?

    I don't totally understand spanning sets... Can anyone explain this problem to me: let V = set of all polynomials with degree of 2 or less (a vector space_ let S = {t + 1, t^2 + 1, t^2 - t} Does S span V? I know that (t^2 + 1) - (t + 1) = t^2 - t But I just don't see what that...
  37. V

    Why Does the Basis (1, 1, 1) Satisfy the Given System of Linear Equations?

    Ok another question: 13. The set of solutions to the system of linear equations a - 2b + c = 0 2a - 3b + c = 0 is a subspace of R^3. Find a basis for this subspace The book claims one of the possible bases is (1, 1, 1) but I don't see how. I mean I realize a = b = c from the...
  38. P

    Help with Vector Space: Real Vector Space Explained

    vector space... help! i just got into vector spaces and i am really stump. okay from teh definition of vector space, it says something... "w/ the operation of mult by a number and addition. more briefly, we refer to V as a real vector space." so from a question from an exercise: determine...
  39. B

    Prove That If rv = 0 Then Either r=0 or v=0

    how do you prove that if v is an element of V (a vector space), and if r is a scalar and if rv = 0, then either r = 0 or v = 0... it seems obvious, but i have no idea how to prove it...
  40. E

    Exploring the Basis of Vector Spaces and Fourier Series in PDEs

    The 3 dimensional space that we inhabit must have a basis of 3 vectors which is fair enough. But in my partial differential equations class in which Fourier series was introduced, it was said that piecewise smooth function space has a basis of an infinite number of vectors. If there is a...
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