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    Re: A sudden plot twist: from CN to cryptograhpy. :)
    From: Bill Lionheart
    Date: 2017 Jul 20, 09:13 +0100

    I work on "inverse problems", things like tomography where the forward
    problem is easy (and generally solved by nature) while the inverse
    problem is hard, typically as it is ill-conditioned. An archetypal
    example of this type of ill-conditioning is finding your position from
    a set of position lines that are close to the same direction.
    I think Tony's idea was that the computational complexity is hard the
    way we want to go. Actually this is true of most non-linear systems of
    equations unless you are lucky enough to find an analytical solution.
    On 19 July 2017 at 21:23, Tony Oz  wrote:
    > Hello!
    > :)
    > Suddenly it occurred to me that certain CN problems are similar to
    > cryptographical: in one direction the solution is (relatively) easy and
    > straightforward, in the other direction - quite difficult and laborious.
    > Consider finding a GC distance between the two points of known coordinates -
    > easy, just use one formula. The reversed problem of finding the initial
    > coordinates from a known distance is impossible, just like the cryptography
    > on elliptic curve(s).
    > (I was thinking about a way to obtain AP coordinates from a set of
    > Ho|GPcoordinates without any plotting - but directly by a formula solving)
    > Regards,
    > Tony
    > View and reply to this message
    Professor of Applied Mathematics

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