<s>
In	O
mathematics	O
,	O
a	O
layer	B-Algorithm
group	I-Algorithm
is	O
a	O
three-dimensional	O
extension	O
of	O
a	O
wallpaper	O
group	O
,	O
with	O
reflections	O
in	O
the	O
third	O
dimension	O
.	O
</s>
<s>
Table	O
of	O
the	O
80	O
layer	B-Algorithm
groups	I-Algorithm
,	O
organized	O
by	O
crystal	O
system	O
or	O
lattice	O
type	O
,	O
and	O
by	O
their	O
point	O
groups	O
:	O
</s>
