... follows

Abundances are referred to as (i)  $n_{\rm X}$ = relative abundance of species X by number, (ii) $\log$    $n_{\rm X}$ = log of above, (iii) $[X]=\log$    $n_{\rm X}$$/$ $n_{\rm X}$$_{\odot}$, representing log abundance relative to solar and (iv) $[X/Fe] = \log ($ $n_{\rm X}$$/$  $n_{\rm Fe}$$)/($ $n_{\rm X}$$/$  $n_{\rm Fe}$$)_{\odot}$, representing the same scaled to allow for the difference between the stellar and solar iron abundance.

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... unchanged

This is actually the description of chaotic behaviour in a mechanical system.

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