Dual basis Definition and 28 Threads

  1. cianfa72

    I Terminologies used to describe tensor product of vector spaces

    Hi, I'm in trouble with the different terminologies used for tensor product of two vectors. Namely a dyadic tensor product of vectors ##u, v \in V## is written as ##u \otimes v##. It is basically a bi-linear map defined on the cartesian product ##V^* \times V^* \rightarrow \mathbb R##. From a...
  2. Z

    Null space of dual map of T = annihilator of range T

    Consider the concepts of dual space, dual basis, dual map, and annihilator. Given a linear map ##T\in L(V,W)##, the dual space of ##T## is the vector space ##V'=L(V,\mathbb{F})## where ##\mathbb{F}## is a field. Note that given any basis ##v_1, ..., v_n## of ##V##, each distinct linear...
  3. A

    I Expressing Vectors of Dual Basis w/Metric Tensor

    I'm trying to understand why it is possible to express vectors ##\mathbf{e}^i## of the dual basis in terms of the vectors ##\mathbf{e}_j## of the original basis through the dual metric tensor ##g^{ij}##, and vice versa, in these ways: ##\mathbf{e}^i=g^{ij}\mathbf{e}_j##...
  4. K

    I Prove that dim(V⊗W)=(dim V)(dim W)

    This proof was in my book. Tensor product definition according to my book: $$V⊗W=\{f: V^*\times W^*\rightarrow k | \textrm {f is bilinear}\}$$ wher ##V^*## and ##W^*## are the dual spaces for V and W respectively. I don't understand the step where they say ##(e_i⊗f_j)(φ,ψ) = φ(e_i)ψ(f_j)##...
  5. K

    Calculate the dual basis and tangent basis vectors

    a) Since ##tan(x/x_0)## is not defined for ##x=\pm\pi/2\cdot x_0## I assume x must be in between those values therefore ##-\pi/2\cdot x_0 < x < \pi/2\cdot x_0## and y can be any real number. Is this the correct answer on a)? b) I can solve x and y for s and t which gives me ##y=y_0\cdot s## and...
  6. K

    I Understanding the concepts of isometric basis and musical isomorphism

    Im very new to the terminologies of isometric basis and musical isomorphism, will appreciate a lot if someone could explain this for me in a simple way for a guy with limited experience in this field. The concrete problem I want to figure out is this: Given: Let ##v_1 = (1,0,0) , v_2 = (1,1,0)...
  7. J

    MHB Showing the Dual Basis is a basis

    I am working through a book with my professor and we read a section on the dual space, $V^*$. It gives the basis dual to the basis of $V$ and proves that this is in fact a basis for $V^*$. Characterized by $\alpha^i(e_j)=\delta_j^i$ I understand the proof given. But he said a different...
  8. L

    B How to find the dual basis vector for the following

    ei=i+j+2vk , how to find the dual basis vector if the above is a natural base?
  9. L

    MHB Question about proof of the linear independence of a dual basis

    This is from Kreyszig's Introductory Functional Analysis Theorem 2.9-1. Let $X$ be an n-dimensional vector space and $E=\{e_1, \cdots, e_n \}$ a basis for $X$. Then $F = \{f_1, \cdots, f_n\}$ given by (6) is a basis for the algebraic dual $X^*$ of $X$, and $\text{dim}X^* = \text{dim}X=n$...
  10. Adrian555

    Natural basis and dual basis of a circular paraboloid

    Hi everyone!I'm trying to obtain the natural and dual basis of a circular paraboloid parametrized by: $$x = \sqrt U cos(V)$$ $$y = \sqrt U sen(V)$$ $$z = U$$ with the inverse relationship: $$V = \arctan \frac{y}{x}$$ $$U = z$$ The natural basis is: $$e_U = \frac{\partial \overrightarrow{r}}...
  11. JTC

    A Understanding the Dual Basis and Its Directions

    Please help. I do understand the representation of a vector as: vi∂xi I also understand the representation of a vector as: vidxi So far, so good. I do understand that when the basis transforms covariantly, the coordinates transform contravariantly, and v.v., etc. Then, I study this thing...
  12. V

    I Confusion about Dual Basis Vectors: Why are these two relationships equal?

    Hello all! I've just started to study general relativity and I'm a bit confused about dual basis vectors. If we have a vector space \textbf{V} and a basis \{\textbf{e}_i\}, I can define a dual basis \{\omega^i\} in \textbf{V}^* such that: \omega^i(\textbf{e}_j) = \delta^i_j But in some pdf and...
  13. Math Amateur

    MHB Dual Vector Space and Dual Basis - another question - Winitzki Section 1-6

    I am reading Segei Winitzki's book: Linear Algebra via Exterior Products ... I am currently focused on Section 1.6: Dual (conjugate) vector space ... ... I need help in order to get a clear understanding of an aspect of the notion or concept of the dual basis \{ e^*_1, e^*_2, \ ... \ ... \...
  14. F

    Prove that three functions form a dual basis

    Homework Statement Homework Equations[/B] The Attempt at a Solution From that point, I don't know what to do. How do I prove linear independence if I have no numerical values? Thank you.
  15. I

    Understanding dual basis & scale factors

    I'm confused by the following passage in our book (translated). An alternative too choosing the normed tangent vectors ##\vec e_i = \frac{1}{h_1}\frac{\partial \vec r}{\partial u_i}## with scale factors ##h_i = \left| \frac{\partial \vec r }{\partial u_i} \right| ## is to choose the normal...
  16. M

    Dual basis and kernel intersection

    The problem statement, all variable Let ##\phi_1,...,\phi_n \in V^*## all different from the zero functional. Prove that ##\{\phi_1,...,\phi_n\}## is basis of ##V^*## if and only if ##\bigcap_{i=1}^n Nu(\phi_i)={0}##. The attempt at a solution. For ##→##: Let ##\{v_1,...,v_n\}## be...
  17. H

    Coordinate and dual basis vectors and metric tensor

    I have been reading an introductory book to General Relativity by H Hobson. I have been following it step by step and now I am stuck. It is stated in the book that: "It is straightforward to show that the coordinate and dual basis vectors themselves are related... "ea = gabeb ..." I have...
  18. S

    Can You Explain the Relationship Between a Basis and Its Dual Basis?

    Hi, I'm learning about vector spaces and I would like to ask some questions about it. Suppose I have a vector space V, and a basis for V \{v_1, ... v_n\}. Then there is a dual space V^* consisting all linear functions whose domain is V and range is ℝ. Then the space V^* has a dual basis \{x_1...
  19. B

    Why Does the Second Equality Hold in Multi-Linear Algebra?

    {(a_i)_j} is the dual basis to the basis {(e_i)_j} I want to show that ((a_i)_1) \wedge (a_i)_2 \wedge... \wedge (a_i)_n ((e_i)_1,(e_i)_2,...,(e_i)_n) = 1 this is exercise 4.1(a) from Spivak. So my approach was: \BigWedge_ L=1^k (a_i)_L ((e_i)_1,...,(e_i)_n) = k! Alt(\BigCross_L=1^k...
  20. S

    A one-form versus a dual basis vector

    Hi everyone, Pardon the neophyte question, but is a one-form the same thing as a dual basis vector? If not, are they related in some way, or completely different concepts/entities? Thank you!
  21. M

    Relationship of Basis to Dual Basis

    If we're working in R^n and we consider the elements of a basis for R^n to be the column vectors of an nxn invertible matrix B, then what is the relationship between B and the matrix whose row vectors represent elements of the corresponding dual basis for R^n*? My guess, which Wikipedia helped...
  22. S

    Finding coefficients using dual basis

    Let V be the space of polynomials of degree 3 or less over \Re. For every \lambda\in\Re the evaluation at \lambda is the map ev_{\lambda} such that V \rightarrow \Re is linear. How do we find the coefficients of ev_{2} in the basis dual to \{1,x,x^2,x^3\}?
  23. B

    Dual basis and differential forms

    I was reading about dual spaces and dual bases in the book Linear Algebra by Friedberg, Spence and Insel (FSI) and they give an example of a linear functional, f_i (x) = a_i where [x]_β = [a_1 a_2 ... a_n] denotes the matrix representation of x in terms of the basis β = {x_1, x_2, ..., x_n} of...
  24. G

    Dual basis problem. (Linear Algebra)

    Homework Statement Prove that if m < n and if y_1,...,y_m are linear functionals on an n-dimensional vector space V, then there exists a non-zero vector x in V such that [x,y_j] = 0 for j = 1,..., m Homework Equations The Attempt at a Solution My thinking is somehow that we...
  25. F

    Abstract Linear Algebra: Dual Basis

    Homework Statement Define a non-zero linear functional y on C^2 such that if x1=(1,1,1) and x2=(1,1,-1), then [x1,y]=[x2,y]=0. Homework Equations N/A The Attempt at a Solution Le X = {x1,x2,...,xn} be a basis in C3 whose first m elements are in M (and form a basis in M). Let X' be...
  26. N

    Is the Dual Basis in Minkowski Space Affected by the Metric Tensor?

    Normally, if you have an orthonormal basis for a space, you can just apply your metric tensor to get your dual basis, since for an orthonormal basis all the dot products between the base vectors will boil down to a Kronecker delta. However, in Minkowski space, the dot product between a unit...
  27. N

    To find dual basis from the inner product Matrix?

    To find dual basis from the inner product Matrix!? Homework Statement WE know the inner product matrix (capital)Gamma and that's all. How do we "construct" a dual basis? Homework Equations The Attempt at a Solution I know that the orthonormal basis is nothing but a dual...
  28. P

    What is the Dual Basis for Linear Algebra?

    [SOLVED] Linear Algebra Dual Basis Let V= R3 and define f1, f2, f3 in V* as follows: f1 = x -2y f2 = x + y +z f3 = y -3z part (a): prove that {f1, f2, f3} is a basis for V* I did this by using the gauss jordan method and showing that {f1, f2, f3} is linearly independent. Now...
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