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- From: benzvi@leibniz.geom.umn.edu (benzvi)
- Newsgroups: sci.math,sci.physics
- Subject: Re: tensors: How about 3rd, 4th rank?
- Message-ID: <1992Aug21.191559.20170@news2.cis.umn.edu>
- Date: 21 Aug 92 19:15:59 GMT
- References: <5130@tuegate.tue.nl> <5134@tuegate.tue.nl> <3djygrk@rpi.edu>
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- Organization: Geometry Center, University of Minnesota
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-
- Just thought I'd liven up the discussion with the ""correct"" ( (: :) )
- definition of a tensor- a (p,q) tensor on a manifold M (tangent
- bundle TM, cotangent bundle TM*) is a section of the vector bundle
- obtained by tensoring TM with itself p times and then tensoring with
- TM* q times. Here the tensoring is the tensor product of
- vector spaces: given two vector spaces over a common scalar field,
- V and W, V(tensor)W is defined as the set of elements
- v(tensor)w (v in V, w in W). This tensoring is a formal operation
- satisfying the relations (v1+v2)(tensor)w=v1(tens)w+v2(tens)w,
- v(tens)(w1+w2)=v(tens)w1+v(tens)w2, and k (v(tens)w)=kv(tens)w=
- v(tens)kw for k a scalar.
- Of course there is arbitrary detail to be added to this explanation...
- For a good treatment of tensors (the nice topological way instead of the
- messy physics/diff geom way with local coordinates) see
- Warner, Foundations of Differentiable Manifolds and Lie Groups.
- (Or see Lang's Algebra for tensor products, or Dubrovin-Fomenko-Novikov
- and Gullot-Hulin-Lafontaine for the diff geom, or........)
- David
-