Notes on computational linguistics.pdf - UCLA Department of ...

Stabler - Lx 185/209 2003
The second file provides the interface to code from Shieber, Schabes, and Pereira (1993):
/* closure-sics.pl
* E. Stabler, 16 Oct 99
* interface to the chart mechanism of Shieber, Schabes & Periera (1993)
*/
:- [’shieberetal93-sics/chart.pl’].
:- [’shieberetal93-sics/agenda.pl’].
:- [’shieberetal93-sics/items.pl’].
:- [’shieberetal93-sics/monitor.pl’].
:- [’shieberetal93-sics/driver’].
:- [’shieberetal93-sics/utilities’].
closure(InitialSet,Closure) :init_chart,
empty_agenda(Empty),
add_items_to_agenda(InitialSet, Empty, Agenda),
exhaust(Agenda),
setof(Member,Indexˆstored(Index,Member),Closure).
% item_to_key/2 should be specialized for the relations being computed
item_to_key(F, Hash) :- hash_term(F, Hash).
(40) The GLC parser that checks the oracle is then:
/* file: glco.pl
* E Stabler, Feb 2000
*/
:- op(1200,xfx,: ˜ ). % this is our object language "if"
:- op(1100,xfx,? ˜ ). % metalanguage provability predicate
[] ? ˜ [].
(S0 ? ˜Goals0) :- infer(S0,Goals0,S,Goals), (S ? ˜Goals). infer([W|S],[W|C],S,C). % shift-complete=scan
infer([W|S],C,S,[-W|C]) :- nrR([-W|C]). % shift
infer(S,RPC,S,DC) :- (A : ˜P+D), preverse(P,RPC,[A|C]), append(D,C,DC). % reduce-complete
infer(S,RPC,S,DAC) :- (A : ˜P+D), preverse(P,RPC,C), nrR([-A|C]), append(D,[-A|C],DAC). % reduce
%preverse(ExpansionD,ReversedExpansionD,RestConstituents)
preverse([E|L],RD,C) :- preverse(L,RD,[-E|C]).
preverse( [], C,C).
append([],L,L).
append([E|L],M,[E|N]) :- append(L,M,N).
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