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Chapter 23: Differential Forms and Matrix-Valued Differential Forms
https://doi.org/10.1142/9789813275386_0023Cited by:0 (Source: Crossref)
Abstract:
We define differential p-forms of class C∞ on an open set Ω of ℝn to be the expressions
ω := n∑j1<j2<⋯ < jpcj1j2⋯jp(X)dxj1∧ dxj2∧ ⋯ ∧ dxjp
where the functions cj1j2…jp ∊ C∞1(Ω) and the integers j1, …, jp lie between 1 and n. Two such differential forms may be added componentwise. One defines the Grabmann product (also called exterior product or wedge product) of a p-form and a q-form as follows: For any permutation σ of the indices j1, …, jp, dxσ(j1)∧ dxσ(j2) ∧⋯ ∧ dxσ(jp) = sgn(σ) dxj1∧ dxj2 ∧⋯ ∧ dxjp
where sgn(σ) denotes the sign of the permutation σ. Let ω′ = n∑k1< k2<⋯ < kqbk1k2⋯kq(X)dxk1∧ dxk2∧ ⋯ ∧ dxkq.