A Hodge Dual as Sequence of Grade Reducing Steps

MisterX
Messages
758
Reaction score
71
If we seek a bijection $$\wedge^p V \to \wedge^{n-p} V$$ for some inner product space ##V##, we might think of starting with the unit ##n##-vector and removing dimensions associated with the original vector in ##\wedge^p V ##. Might this be expressed as a sequence of steps by some binary function ##G##,
$$\star \left( \mathbf{x} \wedge \mathbf{y} \right) = G\Big(\mathbf{x}, G\big( \mathbf{y}, \mathbf{e}_1 \wedge \dots \wedge \mathbf{e}_n\big)\Big) $$
in which case how might we express ##G##?
 
Physics news on Phys.org
MisterX said:
If we seek a bijection $$\wedge^p V \to \wedge^{n-p} V$$ for some inner product space ##V##, we might think of starting with the unit ##n##-vector and removing dimensions associated with the original vector in ##\wedge^p V ##. Might this be expressed as a sequence of steps by some binary function ##G##,
$$\star \left( \mathbf{x} \wedge \mathbf{y} \right) = G\Big(\mathbf{x}, G\big( \mathbf{y}, \mathbf{e}_1 \wedge \dots \wedge \mathbf{e}_n\big)\Big) $$
in which case how might we express ##G##?

May I ask why seek a bijection this way? As you probably know, the dimension of ##\wedge^p V## and ##\wedge^{n-p} V## is ##\binom {n} {p}##. Since they already have the same dimension, there is a vector space isomorphism, which you can find in proofs like http://math.stackexchange.com/quest...ctor-spaces-of-equal-dimension-are-isomorphic. A more interesting question, is whether there is a map which shows that ##\wedge^p V## and ##\wedge^{n-p} V## have the same graded structure. I don't know what grade preserving maps are called. Maybe that is what you are trying to find?
 
Lucas SV said:
May I ask why seek a bijection this way? As you probably know, the dimension of ##\wedge^p V## and ##\wedge^{n-p} V## is ##\binom {n} {p}##. Since they already have the same dimension, there is a vector space isomorphism, which you can find in proofs like http://math.stackexchange.com/quest...ctor-spaces-of-equal-dimension-are-isomorphic. A more interesting question, is whether there is a map which shows that ##\wedge^p V## and ##\wedge^{n-p} V## have the same graded structure. I don't know what grade preserving maps are called. Maybe that is what you are trying to find?
Well I was trying to actually express the map (in a coordinate free way), not just prove it exists. But I was also curious if I could find other uses for this operation.
 
I asked online questions about Proposition 2.1.1: The answer I got is the following: I have some questions about the answer I got. When the person answering says: ##1.## Is the map ##\mathfrak{q}\mapsto \mathfrak{q} A _\mathfrak{p}## from ##A\setminus \mathfrak{p}\to A_\mathfrak{p}##? But I don't understand what the author meant for the rest of the sentence in mathematical notation: ##2.## In the next statement where the author says: How is ##A\to...
The following are taken from the two sources, 1) from this online page and the book An Introduction to Module Theory by: Ibrahim Assem, Flavio U. Coelho. In the Abelian Categories chapter in the module theory text on page 157, right after presenting IV.2.21 Definition, the authors states "Image and coimage may or may not exist, but if they do, then they are unique up to isomorphism (because so are kernels and cokernels). Also in the reference url page above, the authors present two...
When decomposing a representation ##\rho## of a finite group ##G## into irreducible representations, we can find the number of times the representation contains a particular irrep ##\rho_0## through the character inner product $$ \langle \chi, \chi_0\rangle = \frac{1}{|G|} \sum_{g\in G} \chi(g) \chi_0(g)^*$$ where ##\chi## and ##\chi_0## are the characters of ##\rho## and ##\rho_0##, respectively. Since all group elements in the same conjugacy class have the same characters, this may be...
Back
Top