<s>
In	O
geographic	B-Application
information	I-Application
systems	I-Application
,	O
toponym	B-Application
resolution	I-Application
is	O
the	O
relationship	B-Algorithm
process	I-Algorithm
between	O
a	O
toponym	O
,	O
i.e.	O
</s>
<s>
A	O
toponym	B-Application
resolution	I-Application
algorithm	O
is	O
an	O
automatic	O
method	O
that	O
performs	O
a	O
mapping	O
from	O
a	O
toponym	O
to	O
a	O
spatial	O
footprint	O
.	O
</s>
<s>
Some	O
methods	O
for	O
toponym	B-Application
resolution	I-Application
employ	O
a	O
gazetteer	O
of	O
possible	O
mappings	O
between	O
names	O
and	O
spatial	O
footprints	O
.	O
</s>
<s>
The	O
toponym	B-Application
resolution	I-Application
sometimes	O
is	O
a	O
simple	O
conversion	O
from	O
name	O
to	O
abbreviation	O
,	O
in	O
special	O
when	O
the	O
abbreviation	O
is	O
used	O
as	O
standard	O
geocode	O
.	O
</s>
<s>
For	O
example	O
,	O
converting	O
the	O
official	O
country	O
name	O
Afghanistan	O
into	O
an	O
ISO	B-Language
country	I-Language
code	I-Language
,	O
AF	O
.	O
</s>
<s>
In	O
contrast	O
to	O
geocoding	B-Application
of	O
postal	O
addresses	O
,	O
which	O
are	O
typically	O
stored	O
in	O
structured	O
database	O
records	O
,	O
toponym	B-Application
resolution	I-Application
is	O
typically	O
applied	O
to	O
large	O
unstructured	O
text	O
document	O
collections	O
to	O
associate	O
the	O
locations	O
mentioned	O
in	O
them	O
with	O
maps	O
.	O
</s>
<s>
In	O
order	O
to	O
automatically	O
geotag	O
a	O
text	O
document	O
,	O
the	O
following	O
steps	O
are	O
usually	O
undertaken	O
:	O
toponym	O
recognition	O
(	O
i.e.	O
,	O
spotting	O
textual	O
references	O
to	O
geographic	O
locations	O
)	O
and	O
toponym	B-Application
resolution	I-Application
(	O
i.e.	O
,	O
selecting	O
an	O
appropriate	O
location	O
interpretation	O
for	O
each	O
geographic	O
reference	O
)	O
.	O
</s>
<s>
Toponym	O
recognition	O
can	O
be	O
considered	O
as	O
a	O
special	O
case	O
of	O
named-entity	B-General_Concept
recognition	I-General_Concept
where	O
the	O
objective	O
is	O
to	O
merely	O
derive	O
location	O
entities	O
.	O
</s>
<s>
However	O
,	O
the	O
result	O
of	O
named-entity	B-General_Concept
recognition	I-General_Concept
can	O
be	O
further	O
improved	O
using	O
hand-crafted	O
rules	O
or	O
statistical	O
rules	O
.	O
</s>
<s>
This	O
approach	O
fails	O
to	O
pinpoint	O
toponym	O
London	O
as	O
the	O
city	O
located	O
in	O
Ontario	B-Architecture
,	I-Architecture
Canada	I-Architecture
.	O
</s>
<s>
Additionally	O
,	O
toponym	B-Application
resolution	I-Application
does	O
not	O
address	O
metonymy	O
in	O
general	O
.	O
</s>
<s>
Toponym	B-Application
resolution	I-Application
methods	O
can	O
be	O
generally	O
divided	O
into	O
supervised	B-General_Concept
and	O
unsupervised	B-General_Concept
models	O
.	O
</s>
<s>
Supervised	B-General_Concept
methods	O
typically	O
cast	O
the	O
problem	O
as	O
a	O
learning	O
task	O
wherein	O
the	O
model	O
first	O
extracts	O
contextual	O
and	O
non-contextual	O
features	O
and	O
then	O
,	O
a	O
classifier	O
is	O
trained	O
on	O
a	O
labelled	O
dataset	O
.	O
</s>
<s>
On	O
the	O
other	O
hand	O
,	O
unsupervised	B-General_Concept
models	O
do	O
not	O
warrant	O
annotated	O
data	O
.	O
</s>
<s>
They	O
are	O
superior	O
to	O
supervised	B-General_Concept
models	O
when	O
the	O
annotated	O
corpus	O
is	O
not	O
sufficiently	O
large	O
,	O
and	O
supervised	B-General_Concept
models	O
may	O
not	O
generalize	O
well	O
.	O
</s>
<s>
Unsupervised	B-General_Concept
models	O
tend	O
to	O
better	O
exploit	O
the	O
interplay	O
of	O
toponyms	O
mentioned	O
in	O
a	O
document	O
.	O
</s>
<s>
By	O
means	O
of	O
mapping	O
the	O
problem	O
to	O
a	O
conflict-free	O
set	B-Algorithm
cover	I-Algorithm
problem	I-Algorithm
,	O
this	O
model	O
achieves	O
a	O
coherent	O
and	O
robust	O
resolution	O
.	O
</s>
<s>
Furthermore	O
,	O
adopting	O
Wikipedia	O
and	O
knowledge	O
bases	O
have	O
been	O
shown	O
effective	O
in	O
toponym	B-Application
resolution	I-Application
.	O
</s>
<s>
Geoparsing	O
is	O
a	O
special	O
toponym	B-Application
resolution	I-Application
process	O
of	O
converting	O
free-text	O
descriptions	O
of	O
places	O
(	O
such	O
as	O
"	O
twenty	O
miles	O
northeast	O
of	O
Jalalabad	O
"	O
)	O
into	O
unambiguous	O
geographic	O
identifiers	O
,	O
such	O
as	O
geographic	O
coordinates	O
expressed	O
as	O
latitude-longitude	O
.	O
</s>
<s>
With	O
geographic	O
coordinates	O
the	O
features	O
can	O
be	O
mapped	O
and	O
entered	O
into	O
Geographic	B-Application
information	I-Application
systems	I-Application
.	O
</s>
<s>
Geoparsing	O
goes	O
beyond	O
geocoding	B-Application
.	O
</s>
<s>
Geocoding	B-Application
analyzes	O
unambiguous	O
structured	O
location	O
references	O
,	O
such	O
as	O
postal	O
addresses	O
and	O
rigorously	O
formatted	O
numerical	O
coordinates	O
.	O
</s>
