[developers] Expanding a grammar with defaults

[Ann Copestake]

well, if there are no other cases of `/', it's safe!  

I don't think anyone would have a use for persistent defaults, other
than admiring their beauty in the feature structures, unless they'd
written their own code to convert the TDFSs into something.  They
aren't handled by the MRS code and I'm fairly sure that the code that
I used when playing with them never made it into a distributed LKB.

Cheers,

Ann

> 
> G'day,
> 
> I believe that approach should work, assuming all defaults are
> > `lexical' rather than `persistent'.  I'd be happy to try and advise if
> > there seem to be problems
> 
> 
> Thank you.
> 
> Ann
> 
> 
> The value of *description-persistence* is L, and the only default I could
> find was:
> 
> lexeme := canon-sign &
>  [ ORTH [ LIST [ REST #last ],
>           LAST #last ],
>    SYN [ HEAD.TOPIC /l -,
>          LEX +,
>          VAL.GAP <! !> ],
>    SEM [ HOOK [ LTOP #ltop,
>                 INDEX #index ],
>          KEY #key & [ LBL #ltop,
>                       ARG0 #index ],
>          RELS.LIST.FIRST #key ] ].
> 
> So it looks as though we are in luck :-).
> 
> Is there any way of testing for the existence of persistent defaults?
> 
> -- 
> Francis Bond <http://www2.nict.go.jp/x/x161/en/member/bond/>
> NICT Language Infrastructure Group
> 
> --001636e1fcd92a039f0463cad2a1
> Content-Type: text/html; charset=UTF-8
> Content-Transfer-Encoding: quoted-printable
> 
> G&#39;day,<br><br><div class=3D"gmail_quote"><blockquote class=3D"gmail_quo=
> te" style=3D"border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt=
>  0.8ex; padding-left: 1ex;">
> I believe that approach should work, assuming all defaults are<br>
> `lexical&#39; rather than `persistent&#39;. =C2=A0I&#39;d be happy to try a=
> nd advise if<br>
> there seem to be problems</blockquote><div>=C2=A0<br>Thank you.<br><br></di=
> v><blockquote class=3D"gmail_quote" style=3D"border-left: 1px solid rgb(204=
> , 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><font color=3D"=
> #888888">
> Ann</font></blockquote><div>=C2=A0</div><div>The value of *description-pers=
> istence* is L, and the only default I could find was: <br><br>lexeme :=3D c=
> anon-sign &amp;<br>=C2=A0[ ORTH [ LIST [ REST #last ], <br>=C2=A0=C2=A0=C2=
> =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 LAST #last ],<br>
> =C2=A0=C2=A0 SYN [ HEAD.TOPIC /l -,<br>=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
> =C2=A0=C2=A0 LEX +,<br>=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 VAL=
> .GAP &lt;! !&gt; ],<br>=C2=A0=C2=A0 SEM [ HOOK [ LTOP #ltop,<br>=C2=A0=C2=
> =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
> =C2=A0 INDEX #index ],<br>=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 =
> KEY #key &amp; [ LBL #ltop,<br>=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
> =A0=C2=A0 ARG0 #index ],<br>
> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 RELS.LIST.FIRST #key ] ].<=
> br><br>So it looks as though we are in luck :-).<br><br>Is there any way of=
>  testing for the existence of persistent defaults?<br></div></div><br>-- <b=
> r>Francis Bond &lt;<a href=3D"http://www2.nict.go.jp/x/x161/en/member/bond/=
> ">http://www2.nict.go.jp/x/x161/en/member/bond/</a>&gt;<br>
> NICT Language Infrastructure Group<br>
> 
> --001636e1fcd92a039f0463cad2a1--