Simple algorithm question - how to reorder a sequence economically

[Peter Brooks]

On May 24, 11:33 pm, Carlos Nepomuceno <carlosnepomuc... at outlook.com>
wrote:
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> > Date: Fri, 24 May 2013 12:01:35 -0700
> > Subject: Re: Simple algorithm question - how to reorder a sequence economically
> > From: peter.h.m.bro... at gmail.com
> > To: python-l... at python.org
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> > On May 24, 5:00 pm, Carlos Nepomuceno <carlosnepomuc... at outlook.com>
> > wrote:
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> >> I don't know what "spurious evidence of correlation" is. Can you give a mathematical definition?
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> > If I run the simulation with the same sequence, then, because event E1
> > always comes before event E2, somebody might believe that there is a
> > causative connection between them in the world that's being simulated,
> > when, in fact, they only correlate in this way because the sequence is
> > not being shuffled. That's what it means.
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> Correlation does not imply causation. If "somebody" is an expert system and you want to avoid it's recognition and/or triggering of some kind, and you can't or don't want to change it's behavior, you may take the random way because it's cheaper.
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> > Actually it'll be a bit more subtle than that, because each iteration
> > of the simulation updates all nodes in one time interval, the events
> > will not usually show the order of iteration - but, where there are
> > any secondary effects, that are related to the order in which the
> > nodes are updated, these will always happen the same way, which is my
> > concern.
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> You should have a more precise understanding of the dependence of the variables you taking in consideration before randomizing the series of events your are using for tests.
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If the scenario could be modelled mathematically, then there'd be no
point in writing the simulation.