List::Compare can check for subsets and can check if two arrays are equivalent.

#   is_LsubsetR() 
#Return a true value if the first argument passed to the
#constructor ('L' for 'left') is a subset of the second 
#argument passed to the constructor ('R' for 'right').

    $LR = $lc->is_LsubsetR;
#Return a true value if R is a subset of L.

    $RL = $lc->is_RsubsetL;
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