Good point; in the olden days of prolog only the SLD search strategy came out of the box, and you had to roll your own if you wanted others. However, happily a

Good point; in the olden days of prolog only the SLD search strategy came out of the box, and you had to roll your own if you wanted others. However, happily a lot of the tabled programming research from the XSB prolog group (and others) has osmosed out into the mainstream prolog implementations by now.