Math 2.0

Linear and multilinear algebra; matrix theory Definition

Exterior algebra

Builds on Vector spaceTensor product of vector spaces

Definition

Let FF be a field and let VV be a vector space over FF. Let T(V)=⨁k≥0V⊗kT(V) = \bigoplus_{k \ge 0} V^{\otimes k} be the tensor algebra of VV, where V⊗0=FV^{\otimes 0} = F and the product is the tensor product. Let II be the two-sided ideal of T(V)T(V) generated by the elements v⊗vv \otimes v for v∈Vv \in V. The exterior algebra of VV is the quotient algebra Λ(V)=T(V)/I\Lambda(V) = T(V) / I. The product in Λ(V)\Lambda(V) is written ∧\wedge.

Remarks

For all u,v∈Vu, v \in V, v∧v=0v \wedge v = 0 and u∧v=−v∧uu \wedge v = -v \wedge u. The image of V⊗kV^{\otimes k} is the kk-th exterior power Λk(V)\Lambda^k(V); if dim⁡V=n\dim V = n, then dim⁡Λk(V)=(nk)\dim \Lambda^k(V) = \binom{n}{k} and dim⁡Λ(V)=2n\dim \Lambda(V) = 2^n. If (e1,…,en)(e_1, \dots, e_n) is a basis of VV, then Λn(V)\Lambda^n(V) is spanned by e1∧⋯∧ene_1 \wedge \cdots \wedge e_n. For vj=∑iaijeiv_j = \sum_i a_{ij} e_i, v1∧⋯∧vn=det⁡(aij) e1∧⋯∧env_1 \wedge \cdots \wedge v_n = \det(a_{ij})\, e_1 \wedge \cdots \wedge e_n.

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Tag08HK38GCSM
URIm2://08HK38GCSM
Kinddefinition
WritingW1 stated
MSC15A75
DefinesExterior algebra
UsesVector space, Tensor product of vector spaces

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