note tilly Very nice. I tried several times without success to come up with a good non-recursive solution. The above not only is short, but it really does the binary search, and applying standard golfing techniques, it comes up a winner at 55: <code> sub f{ ($s,$t)=@_;$t=$$t{$$t{d}gt$s?l:r}while$t&&$$t{d}ne$s;$t } </code> (Or 57 if you add [my] to kill side effects. Still better than anything I thought of.)<P> Note that this is much less readable than what [tye] wrote, but every transformation is fairly mechanical compression of the code... 73900 73914