nested-loop/nested-block join is an approach that could be used when there are limited main memory buffers available to bring in the participating relations fully. given that one buffer is reserved for reading from the inner relation, another one for writing to the output file, there are (nb - 2) buffers allocated for reading from the outer relation where where nb is the number of main memory buffers available. prove that it is almost always advantageous to use the relation with fewer disk blocks as the outer-loop file in the nested-loop join algorithm when we are estimating its cost function (measured by the total disk block access cost to secondary storage).