If the arrays don't contain duplicate elements:

$c{$_}++ foreach @a;
$c{$_}++ foreach @b;

@c = grep { $c{$_} != 2 } @a;
@d = grep { $c{$_} != 2 } @b;

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In reply to Re: Algorithm for cancelling common factors between two lists of multiplicands by ikegami
in thread Algorithm for cancelling common factors between two lists of multiplicands by BrowserUk

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