[basex-talk] Sequence comparison

Hi, I have to compare two sequences and find common items, irrespective of their positions: for $a in (1,2,3,5,3) for $u in (1,3,2,3) where $a = $u group by $o := $a return <c>{$a}</c> This returns <c>1</c> <c>2</c> <c>3 3 3 3</c> I would like 3 to be repeated only twice (i.e., each item in the first sequence should pair only with one in the second sentence): is there an XQuery "trick" for that in the FLOWR expression?