<s>
Link	B-General_Concept
grammar	I-General_Concept
(	O
LG	O
)	O
is	O
a	O
theory	O
of	O
syntax	B-Application
by	O
Davy	O
Temperley	O
and	O
Daniel	O
Sleator	O
which	O
builds	O
relations	O
between	O
pairs	O
of	O
words	O
,	O
rather	O
than	O
constructing	O
constituents	O
in	O
a	O
phrase	O
structure	O
hierarchy	O
.	O
</s>
<s>
Link	B-General_Concept
grammar	I-General_Concept
is	O
similar	O
to	O
dependency	O
grammar	O
,	O
but	O
dependency	O
grammar	O
includes	O
a	O
head-dependent	O
relationship	O
,	O
whereas	O
Link	B-General_Concept
Grammar	I-General_Concept
makes	O
the	O
head-dependent	O
relationship	O
optional	O
(	O
links	O
need	O
not	O
indicate	O
direction	O
)	O
.	O
</s>
<s>
Colored	O
Multiplanar	O
Link	B-General_Concept
Grammar	I-General_Concept
(	O
CMLG	O
)	O
is	O
an	O
extension	O
of	O
LG	O
allowing	O
crossing	O
relations	O
between	O
pairs	O
of	O
words	O
.	O
</s>
<s>
The	O
relationship	O
between	O
words	O
is	O
indicated	O
with	O
link	O
types	O
,	O
thus	O
making	O
the	O
Link	B-General_Concept
grammar	I-General_Concept
closely	O
related	O
to	O
certain	O
categorial	O
grammars	O
.	O
</s>
<s>
Link	B-General_Concept
grammar	I-General_Concept
connects	O
the	O
words	O
in	O
a	O
sentence	O
with	O
links	O
,	O
similar	O
in	O
form	O
to	O
a	O
catena	O
.	O
</s>
<s>
Unlike	O
the	O
catena	O
or	O
a	O
traditional	O
dependency	O
grammar	O
,	O
the	O
marking	O
of	O
the	O
head-dependent	O
relationship	O
is	O
optional	O
for	O
most	O
languages	O
,	O
becoming	O
mandatory	O
only	O
in	O
free-word-order	O
languages	O
(	O
such	O
as	O
Turkish	O
,	O
Finnish	O
,	O
Hungarian	O
,	O
Lithuanian	O
)	O
.	O
</s>
<s>
For	O
free	B-Application
word-order	O
languages	O
,	O
this	O
can	O
no	O
longer	O
hold	O
,	O
and	O
a	O
link	O
between	O
the	O
subject	O
and	O
verb	O
must	O
contain	O
an	O
explicit	O
directional	O
arrow	O
to	O
indicate	O
which	O
of	O
the	O
two	O
words	O
is	O
which	O
.	O
</s>
<s>
Link	B-General_Concept
grammar	I-General_Concept
also	O
differs	O
from	O
traditional	O
dependency	O
grammars	O
by	O
allowing	O
cyclic	O
relations	O
between	O
words	O
.	O
</s>
<s>
Parsing	O
is	O
performed	O
in	O
analogy	O
to	O
assembling	O
a	O
jigsaw	B-Application
puzzle	I-Application
(	O
representing	O
the	O
parsed	O
sentence	O
)	O
from	O
puzzle	O
pieces	O
(	O
representing	O
individual	O
words	O
)	O
.	O
</s>
<s>
A	O
language	O
is	O
represented	O
by	O
means	O
of	O
a	O
dictionary	O
or	O
lexis	O
,	O
which	O
consists	O
of	O
words	O
and	O
the	O
set	O
of	O
allowed	O
"	O
jigsaw	B-Application
puzzle	I-Application
shapes	O
"	O
that	O
each	O
word	O
can	O
have	O
.	O
</s>
<s>
Connectors	O
can	O
have	O
an	O
optional	O
floating-point	B-Algorithm
cost	O
markup	O
,	O
so	O
that	O
some	O
are	O
"	O
cheaper	O
"	O
to	O
use	O
than	O
others	O
,	O
thus	O
giving	O
preference	O
to	O
certain	O
parses	O
over	O
others	O
.	O
</s>
<s>
The	O
assignment	O
of	O
a	O
log-likelihood	O
to	O
linkages	O
allows	O
link	B-General_Concept
grammar	I-General_Concept
to	O
implement	O
the	O
semantic	O
selection	O
of	O
predicate-argument	O
relationships	O
.	O
</s>
<s>
In	O
this	O
way	O
,	O
link	B-General_Concept
grammar	I-General_Concept
embodies	O
some	O
of	O
the	O
ideas	O
present	O
in	O
operator	O
grammar	O
.	O
</s>
<s>
This	O
makes	O
Link	B-General_Concept
Grammar	I-General_Concept
compatible	O
with	O
machine	O
learning	O
techniques	O
such	O
as	O
hidden	O
Markov	O
models	O
and	O
the	O
Viterbi	B-Algorithm
algorithm	I-Algorithm
,	O
because	O
the	O
link	O
costs	O
correspond	O
to	O
the	O
link	O
weights	O
in	O
Markov	O
networks	O
or	O
Bayesian	O
networks	O
.	O
</s>
<s>
The	O
Link	B-General_Concept
Grammar	I-General_Concept
link	O
types	O
can	O
be	O
understood	O
to	O
be	O
the	O
types	O
in	O
the	O
sense	O
of	O
type	O
theory	O
.	O
</s>
<s>
In	O
effect	O
,	O
the	O
Link	B-General_Concept
Grammar	I-General_Concept
can	O
be	O
used	O
to	O
model	O
the	O
internal	O
language	O
of	O
certain	O
(	O
non-symmetric	O
)	O
compact	O
closed	O
categories	O
,	O
such	O
as	O
pregroup	O
grammars	O
.	O
</s>
<s>
In	O
this	O
sense	O
,	O
Link	B-General_Concept
Grammar	I-General_Concept
appears	O
to	O
be	O
isomorphic	O
or	O
homomorphic	O
to	O
some	O
categorial	O
grammars	O
.	O
</s>
<s>
The	O
contraction	O
rules	O
(	O
inference	O
rules	O
)	O
of	O
the	O
Lambek	O
calculus	O
can	O
be	O
mapped	O
to	O
the	O
connecting	O
of	O
connectors	O
in	O
Link	B-General_Concept
Grammar	I-General_Concept
.	O
</s>
<s>
The	O
Vietnamese	O
language	O
sentence	O
"	O
Bữa	O
tiệc	O
hôm	O
qua	O
là	O
một	O
thành	O
công	O
lớn	O
"	O
-	O
"	O
The	O
party	O
yesterday	O
was	O
a	O
great	O
success	O
"	O
may	O
be	O
parsed	O
as	O
follows	O
:	O
</s>
<s>
The	O
link	B-General_Concept
grammar	I-General_Concept
syntax	B-Application
parser	B-Language
is	O
a	O
library	B-Library
for	O
natural	B-Language
language	I-Language
processing	I-Language
written	O
in	O
C	B-Language
.	O
It	O
is	O
available	O
under	O
the	O
LGPL	B-Application
license	I-Application
.	O
</s>
<s>
The	O
parser	B-Language
is	O
an	O
ongoing	O
project	O
.	O
</s>
<s>
Recent	O
versions	O
include	O
improved	O
sentence	O
coverage	O
,	O
Russian	O
,	O
Persian	O
and	O
Arabic	O
language	O
support	O
,	O
prototypes	O
for	O
German	O
,	O
Hebrew	O
,	O
Lithuanian	O
,	O
Vietnamese	O
and	O
Turkish	O
,	O
and	O
programming	O
API	O
's	O
for	O
Python	B-Language
,	O
Java	B-Language
,	O
Common	B-Language
LISP	I-Language
,	O
AutoIt	B-Language
and	O
OCaml	B-Language
,	O
with	O
3rd-party	O
bindings	O
for	O
Perl	B-Language
,	O
Ruby	B-Language
and	O
JavaScript	B-Language
node.js	B-Language
.	O
</s>
<s>
The	O
link-parser	O
program	O
along	O
with	O
rules	O
and	O
word	O
lists	O
for	O
English	O
may	O
be	O
found	O
in	O
standard	O
Linux	B-Application
distributions	I-Application
,	O
e.g.	O
,	O
as	O
a	O
Debian	O
package	O
,	O
although	O
many	O
of	O
these	O
are	O
years	O
out	O
of	O
date	O
.	O
</s>
<s>
AbiWord	B-Language
,	O
a	O
free	B-Application
word	B-General_Concept
processor	I-General_Concept
,	O
uses	O
Link	B-General_Concept
Grammar	I-General_Concept
for	O
on-the-fly	O
grammar	O
checking	O
.	O
</s>
<s>
The	O
semantic	O
relationship	O
extractor	O
RelEx	O
,	O
layered	O
on	O
top	O
of	O
the	O
Link	B-General_Concept
Grammar	I-General_Concept
library	B-Library
,	O
generates	O
a	O
dependency	O
grammar	O
output	O
by	O
making	O
explicit	O
the	O
semantic	O
relationships	O
between	O
words	O
in	O
a	O
sentence	O
.	O
</s>
<s>
It	O
includes	O
a	O
compatibility	O
mode	O
to	O
generate	O
dependency	O
output	O
compatible	O
with	O
the	O
Stanford	O
parser	B-Language
,	O
and	O
Penn	O
Treebank-compatible	O
POS	O
tagging	O
.	O
</s>
<s>
events	O
described	O
in	O
news	O
articles	O
,	O
as	O
well	O
as	O
experimental	O
machine	B-Application
translation	I-Application
systems	I-Application
from	O
English	O
to	O
German	O
,	O
Turkish	O
,	O
Indonesian	O
.	O
</s>
<s>
The	O
Link	B-General_Concept
Grammar	I-General_Concept
link	O
dictionary	O
is	O
used	O
to	O
generate	O
and	O
verify	O
the	O
syntactic	O
correctness	O
of	O
three	O
different	O
natural	B-General_Concept
language	I-General_Concept
generation	I-General_Concept
systems	O
:	O
NLGen	O
,	O
NLGen2	O
and	O
microplanner/surreal	O
.	O
</s>
<s>
It	O
is	O
also	O
used	O
as	O
a	O
part	O
of	O
the	O
NLP	B-Language
pipeline	O
in	O
the	O
OpenCog	B-Application
AI	O
project	O
.	O
</s>
