  Mode-directed tabling is an extension to the tabling technique that supports
the definition of mode operators for specifying how answers are inserted into
the table space. In this paper, we focus our discussion on the efficient
support for mode directed-tabling in the YapTab tabling system. We discuss 7
different mode operators and explain how we have extended and optimized
YapTab's table space organization to support them. Initial experimental results
show that our implementation compares favorably with the B-Prolog and XSB
state-of-the-art Prolog tabling systems.
