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@c This document is part of the Liza Data Collection Framework manual.
@c Copyright (C) 2017 R-T Specialty, LLC.
@c
@c Permission is granted to copy, distribute and/or modify this document
@c under the terms of the GNU Free Documentation License, Version 1.3
@c or any later version published by the Free Software Foundation;
@c with no Invariant Sections, no Front-Cover Texts, and no Back-Cover
@c Texts. A copy of the license is included in the section entitled ``GNU
@c Free Documentation License''.
@node Predicate System
@chapter Predicate System
@maintstart
@footnote{
New programs (using the old incarnation of TAME) use the classifier
embedded into the rater by TAME.
Old ones, however, still use the @dfn{Global Classifier}.
This system isn't as well tested as TAME's@mdash{
}which needs to work properly for the sake of calculating premium@mdash{
}and has suffered from a number of bugs in the past.
The solution is to migrate all programs to TAME and remove that old
code.}
@maintend
@tip{
For a practical application of these concepts, see its use in the
Program@tie{}XML (@pxref{Specifying Predicates}).}
@cindex Predicate
@cindex Classifier
@cindex Applicability
@cindex Domain of discourse, Predicate
The @dfn{predicate system} determines the @dfn{applicability} of
certain objects (like questions and assertions) by associating them
with predicates.
The domain of discourse (variables which may be quantified) is listed
in @ref{t:predicate-dod}.
What it means for some object to be applicable depends on the context.
@float Table, t:predicate-dod
@multitable @columnfractions 0.25 0.10 0.65
@headitem Type @tab Prefix @tab Description
@item Classifications
@tab @emph{None}
@tab Results of applying an external @dfn{classifier} to the bucket
(@pxref{Bucket}).
@item Bucket Truth Predicate
@tab @code{q:}
@tab
Whether the given name in the bucket (@pxref{Bucket}) is
non-empty and non-zero.
The prefix @samp{q:} refers to its most common use
case---questions (@pxref{Program UI,,Program@tie{}UI}).
@end multitable
@caption{Predicate system domain of discourse}
@end float
This system is limited to existential quantification over the domain
of discourse.
For other quantifiers and higher-order logic,
defer to one of the systems that contributes to the domain of
discourse,
like the classifier.@footnote{
This is usually TAME.
The Program XML also supports inline classifications
with TAME's syntax (@pxref{Specifying Predicates}).}
Predicates are usually specified in the Program XML
(@pxref{Specifying Predicates}) and compiled into the program
(@pxref{Program}).