Sender: lojban@googlegroups.com
Date: Sat, 11 Apr 2020 07:35:55 -0700 (PDT)
From: Gleki Arxokuna <gleki.is.my.name@gmail.com>
To: lojban <lojban@googlegroups.com>
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Subject: [lojban] Re: Where is the latest/official PEG grammar?
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Em s=C3=A1bado, 11 de abril de 2020 06:22:41 UTC+3,=20
scope845hlang343jbo@icebubble.org escreveu:
>
> Bob LeChevalier <lojbab@lojban.org> writes:=20
>
> > I don't know why those names are used in any particular PEG=20
> > grammar.=20
>
> ...=20
>
> > For the tag "anaphoracataphora, I suspect that is not a "bug" because=
=20
> > anaphora and cataphora are identical in term of grammar so it is=20
> > merely a naming convention whether to include some separator between=20
> > the two words or not.  I don't know what construct "openclosed" refers=
=20
> > to, but likely it also is a conflation of two types of constructs with=
=20
> > the same grammar.=20
>
> No, these are not the names of non-terminals in the PEG, they appear in=
=20
> the text of comments in the PEG.  They should read "anaphora/cataphora",=
=20
> "open/closed", etc.  It's as if someone did a global=20
> s|([a-zA-Z])/([a-zA-Z])|\1\2| search and replace on the grammar.  The=20
> fact that nobody seems to have noticed these errors strongly suggests=20
> that these PEG versions of the grammar have not been given sufficient=20
> attention.  (doi camxes)=20
>
> > The latest *official* grammar remains the YACC grammar included in The=
=20
> > Complete Lojban Language since its publication in 1997. There have=20
> > been attempts to redevelop the grammar in a PEG form, but NONE of the=
=20
> > PEG grammars has been certified by byfy (or its new successor group)=20
> > as an official replacement for that old one,=20
>
> What are we waiting for?=20


PEG has its own deficiencies.
=20

>  Lojban has been around since 1985 bi'o 1987,=20
> yet we still don't have a complete grammar or a correct parser.  The=20
> YACC has received official blessing, but it's not complete.  Handling of=
=20
> elidable terminators is hand-hacked into the code.  The lexer is also=20
> hand-coded, and implements only a good approximation to Lojban=20
> morphology.  So far, we have neither a complete specification of the=20
> language, nor a fully correct parser.=20
>
>
True. PEG won't put us forward significantly.
=20

> > My understanding is that they are more-or-less equivalent to the old=20
> > YACC grammar, but I don't know that this equivalence was ever formally=
=20
> > proven.=20
>
> Maybe that's what we're waiting for?  A proof that the PEG grammar is=20
> backward-compatible with the YACC? =20


Its not backward compatible by definition.
=20

> =20

=20

> IfIf so, the second half of Bryan=20
> Ford's thesis paper on PEGs describes how to transform parsing=20
> expressions into other forms which could be compared with the YACC.


Transformation doesn't necessarily imply equivalence.
=20

>
>
> For reference, that thesis paper is: http://bford.info/pub/lang/peg.pdf=
=20
>

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<div dir=3D"ltr"><br><br>Em s=C3=A1bado, 11 de abril de 2020 06:22:41 UTC+3=
, scope845hlang343jbo@icebubble.org  escreveu:<blockquote class=3D"gmail_qu=
ote" style=3D"margin: 0;margin-left: 0.8ex;border-left: 1px #ccc solid;padd=
ing-left: 1ex;">Bob LeChevalier &lt;<a href=3D"mailto:lojbab@lojban.org" ta=
rget=3D"_blank" rel=3D"nofollow" onmousedown=3D"this.href=3D&#39;mailto:loj=
bab@lojban.org&#39;;return true;" onclick=3D"this.href=3D&#39;mailto:lojbab=
@lojban.org&#39;;return true;">lojbab@lojban.org</a>&gt; writes:
<br>
<br>&gt; I don&#39;t know why those names are used in any particular PEG
<br>&gt; grammar.
<br>
<br>...
<br>
<br>&gt; For the tag &quot;anaphoracataphora, I suspect that is not a &quot=
;bug&quot; because
<br>&gt; anaphora and cataphora are identical in term of grammar so it is
<br>&gt; merely a naming convention whether to include some separator betwe=
en
<br>&gt; the two words or not. =C2=A0I don&#39;t know what construct &quot;=
openclosed&quot; refers
<br>&gt; to, but likely it also is a conflation of two types of constructs =
with
<br>&gt; the same grammar.
<br>
<br>No, these are not the names of non-terminals in the PEG, they appear in
<br>the text of comments in the PEG. =C2=A0They should read &quot;anaphora/=
cataphora&quot;,
<br>&quot;open/closed&quot;, etc. =C2=A0It&#39;s as if someone did a global
<br>s|([a-zA-Z])/([a-zA-Z])|\1\2| search and replace on the grammar. =C2=A0=
The
<br>fact that nobody seems to have noticed these errors strongly suggests
<br>that these PEG versions of the grammar have not been given sufficient
<br>attention. =C2=A0(doi camxes)
<br>
<br>&gt; The latest *official* grammar remains the YACC grammar included in=
 The
<br>&gt; Complete Lojban Language since its publication in 1997. There have
<br>&gt; been attempts to redevelop the grammar in a PEG form, but NONE of =
the
<br>&gt; PEG grammars has been certified by byfy (or its new successor grou=
p)
<br>&gt; as an official replacement for that old one,
<br>
<br>What are we waiting for? </blockquote><div><br></div><div>PEG has its o=
wn deficiencies.</div><div>=C2=A0</div><blockquote class=3D"gmail_quote" st=
yle=3D"margin: 0;margin-left: 0.8ex;border-left: 1px #ccc solid;padding-lef=
t: 1ex;">=C2=A0Lojban has been around since 1985 bi&#39;o 1987,
<br>yet we still don&#39;t have a complete grammar or a correct parser. =C2=
=A0The
<br>YACC has received official blessing, but it&#39;s not complete. =C2=A0H=
andling of
<br>elidable terminators is hand-hacked into the code. =C2=A0The lexer is a=
lso
<br>hand-coded, and implements only a good approximation to Lojban
<br>morphology. =C2=A0So far, we have neither a complete specification of t=
he
<br>language, nor a fully correct parser.
<br>
<br></blockquote><div><br></div><div>True. PEG won&#39;t put us forward sig=
nificantly.</div><div>=C2=A0</div><blockquote class=3D"gmail_quote" style=
=3D"margin: 0;margin-left: 0.8ex;border-left: 1px #ccc solid;padding-left: =
1ex;">&gt; My understanding is that they are more-or-less equivalent to the=
 old
<br>&gt; YACC grammar, but I don&#39;t know that this equivalence was ever =
formally
<br>&gt; proven.
<br>
<br>Maybe that&#39;s what we&#39;re waiting for? =C2=A0A proof that the PEG=
 grammar is
<br>backward-compatible with the YACC?=C2=A0 </blockquote><div><br></div><d=
iv>Its not backward compatible by definition.</div><div>=C2=A0</div><blockq=
uote class=3D"gmail_quote" style=3D"margin: 0;margin-left: 0.8ex;border-lef=
t: 1px #ccc solid;padding-left: 1ex;">=C2=A0</blockquote><div>=C2=A0</div><=
blockquote class=3D"gmail_quote" style=3D"margin: 0;margin-left: 0.8ex;bord=
er-left: 1px #ccc solid;padding-left: 1ex;">IfIf so, the second half of Bry=
an
<br>Ford&#39;s thesis paper on PEGs describes how to transform parsing
<br>expressions into other forms which could be compared with the YACC.</bl=
ockquote><div><br></div><div>Transformation doesn&#39;t necessarily imply e=
quivalence.</div><div>=C2=A0</div><blockquote class=3D"gmail_quote" style=
=3D"margin: 0;margin-left: 0.8ex;border-left: 1px #ccc solid;padding-left: =
1ex;">
<br>
<br>For reference, that thesis paper is: <a href=3D"http://bford.info/pub/l=
ang/peg.pdf" target=3D"_blank" rel=3D"nofollow" onmousedown=3D"this.href=3D=
&#39;http://www.google.com/url?q\x3dhttp%3A%2F%2Fbford.info%2Fpub%2Flang%2F=
peg.pdf\x26sa\x3dD\x26sntz\x3d1\x26usg\x3dAFQjCNHji58DHqgANwlntZ1xAk3L5I_Xp=
g&#39;;return true;" onclick=3D"this.href=3D&#39;http://www.google.com/url?=
q\x3dhttp%3A%2F%2Fbford.info%2Fpub%2Flang%2Fpeg.pdf\x26sa\x3dD\x26sntz\x3d1=
\x26usg\x3dAFQjCNHji58DHqgANwlntZ1xAk3L5I_Xpg&#39;;return true;">http://bfo=
rd.info/pub/lang/<wbr>peg.pdf</a>
<br></blockquote></div>

<p></p>

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