% % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % %
%                                                                           %
% File:            fldcons.dtr                                              %
% Purpose:         construction of feature-logic descriptions               %
% Author:          James Kilbury, 2 February 1993                           %
% Email:           kilbury@ling.uni-duesseldorf.de                          %
% Address:         U Drf, Universitaetsstr. 1, D-40225 Duesseldorf, Germany %
% Related files:   fldpatr2.dtr, fldqpatr.dtr, fldtest.dtr, englex2.dtr     %
% Version:         2.06 (20 September 1994)                                 %
%                                                                           %
%      Copyright (c) University of Duesseldorf 1994.  All rights reserved.  %
%                                                                           %
% % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % %

# node ^  ~  |  ||  |||  |'  ||'  |||' .

% Such a declaration must be added once facilities are available in QDATR:
% # vars $A: [any attribute except *].

% visible nodes employed in DATR encodings of concrete lexica % % % % % % % %
%               in addition to  ^ ~ |  below under 'general path transducers'

FS :
% constructs a formula in a feature logic that describes a feature structure
    <$Attribute> == "< FS_Path >"  FL_Fmlas:<> .

LIST :
% special node for FSs that encode lists with fi(rst) and re(st)
    <> == FS:<fi re ^>.

ATOM :
% constructs the formula assigning an atomic value to a leaf of a FS
    <$Value *> == Path_Expr:<>  Value_at_Path&  $Value .

VAR :
% analogue of ATOM for anonymous variables
    <> == ATOM:< Anon_Var& >.

RP :
% constructs a formula expressing reentrancy of two paths
    <> == Path_Expr:< ||| >  Reentrancy&  Path_Expr  Conjunction& .


% nodes that are invisible in concrete lexica % % % % % % % % % % % % % % % %

FS_Path :
% constructs a DATR path to be queried in a concrete lexicon
    <$Attribute> == ||'  $Attribute  *  * .

FL_Fmlas :
% recursively constructs the further formulas of a FL description of a FS
    <*> ==
    <$A> == Conjunction&  "< FS_Path >"  <> .

Path_Expr :
% constructs the FL expression built from a FS variable and attribute path
    <> == LBracket&  Variable&  FS_at_Path&  FL_Path:<>  RBracket&
    <*> == Variable&.

FL_Path :
% recursively constructs a path of attributes in a feature logic
    <$Attribute> == $Attribute  FL_Path_Rest:<> .

FL_Path_Rest :
% introduces any further path connectives and attributes
    <*> ==
    <$A> == Path_Connective&  $A  <> .


% general path transducers  % % % % % % % % % % % % % % % % % % % % % % % % % 

^ :
% transduces  beta * alpha * gamma  to  * alpha beta *
    <> == *  ||'  | .

~ :
% transduces  beta * alpha beta * gamma  to  alpha *
    <> == PRev$:< PCutoff$:< PRev$:< | >  *  PRev$:< || >  * > >  * .


| :
% appends * to the sequence returned by |'
    <> == |'  * .

|' :
% transduces the prefix up to * of a path to a sequence 
    <> ==
    <*> ==
    <$A> == $A  <> .

|| :
% appends * to the sequence returned by ||'
    <> == ||'  * .

||' :
% cuts off the first prefix up to * of a path, and then
% if the rest path has a prefix  alpha *, returns the sequence alpha
% and otherwise returns the empty sequence
    <*> == <case$ Bounded$:<> >
    <$A> == <>
    <case$ false> ==
    <case$ true> == |':<>.

||| : 
% appends * to the sequence returned by |||'
    <> == |||' * .

|||' :
% like ||' but for the third prefix  alpha *  (if present) of a path
    <*> == <case$ Bounded$:<> >
    <$A> == <>
    <case$ false> ==
    <case$ true> == ||':<>.
    
Bounded$ :
    <> == false
    <*> == true
    <$A> == <>.

PRev$ :
% transduces  a1 ... an * gamma  to  an ... a1  (i.e. the reverse sequence)
    <*> ==
    <$A> == <>  $A .

PCutoff$ :
% transduces  alpha * alpha beta * gamma  to  beta *
    <*> == |:<>
    <$A> == PCut$:< <> >.

PCut$ :
% transduces  a alpha * gamma  to  alpha *
    <$A> == |:<>.


% The next line is the Revision Control System Id: do not delete it.
% $Id: archive.dtr,v 1.1 1997/04/09 20:40:33 root Exp $