• External differential

    From federation2005@netzero.com@21:1/5 to All on Fri Sep 4 05:00:25 2015
    On Wednesday, December 17, 2014 at 10:58:10 AM UTC-6, Alexey Popov

    However the main question remains:
    Why an external differential exists in multiple different situations?

    The key underlying structures and concepts are: Natural Bundles,
    Natural Operations and Natural Objects. I've not seen a good or simple definition of any of these things until just now ... http://ncatlab.org/nlab/show/natural+bundle

    The "definition" I've been going on up to now is that a natural object
    is whatever you can do a Lie Derivative on (so technically this
    statement is a conjecture of mine though probably a well-known result).

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