\subsection{The TMS}

The following predicates are used to access the tms information
associated with \pfc\ facts.

\gloss{justification(+P,-J)\\
	justification(+P,-Js)}

\prolog{justification(P,J)} is true if one of the justifications for
fact P is J, where J is a list of \pfc\ facts and rules which taken
together deduce P.  Backtracking into this predicate can produce
additional justifications.  If the fact was added by the user, then
one of the justifications will be the list \prolog{[user]}.
\prolog{justifications(P,Js)} is provided for convenience.  It binds
\prolog{Js} to a list of all justifications returned by
\prolog(justification/2).  

\gloss{base(+P,-Ps)}

\gloss{assumptions(+P,-Ps)}

\gloss{pfcChild(+P,-Q)\\
	pfcChildren(+P,-Qs)}

\gloss{pfcDescendant(+P,-Q)\\
	pfcDescendants(+P,-Qs)}