<s>
Proximity	B-Algorithm
problems	I-Algorithm
is	O
a	O
class	O
of	O
problems	O
in	O
computational	O
geometry	O
which	O
involve	O
estimation	O
of	O
distances	O
between	O
geometric	O
objects	O
.	O
</s>
<s>
A	O
subset	O
of	O
these	O
problems	O
stated	O
in	O
terms	O
of	O
points	O
only	O
are	O
sometimes	O
referred	O
to	O
as	O
closest	B-Algorithm
point	I-Algorithm
problems	I-Algorithm
,	O
although	O
the	O
term	O
"	O
closest	B-Algorithm
point	I-Algorithm
problem	I-Algorithm
"	O
is	O
also	O
used	O
synonymously	O
to	O
the	O
nearest	B-Algorithm
neighbor	I-Algorithm
search	I-Algorithm
.	O
</s>
<s>
Geometric	B-Algorithm
spanner	I-Algorithm
,	O
a	O
weighted	O
graph	O
over	O
a	O
set	O
of	O
points	O
as	O
its	O
vertices	O
which	O
for	O
every	O
pair	O
of	O
vertices	O
has	O
a	O
path	O
between	O
them	O
of	O
weight	O
at	O
most	O
'	O
k	O
 '	O
times	O
the	O
spatial	O
distance	O
between	O
these	O
points	O
for	O
a	O
fixed	O
'	O
k	O
 '	O
.	O
</s>
