<s>
Hierarchical	B-Algorithm
classification	I-Algorithm
is	O
a	O
system	O
of	O
grouping	O
things	O
according	O
to	O
a	O
hierarchy	O
.	O
</s>
<s>
In	O
the	O
field	O
of	O
machine	O
learning	O
,	O
hierarchical	B-Algorithm
classification	I-Algorithm
is	O
sometimes	O
referred	O
to	O
as	O
instance	O
space	O
decomposition	O
,	O
which	O
splits	O
a	O
complete	O
multi-class	B-General_Concept
problem	O
into	O
a	O
set	O
of	O
smaller	O
classification	O
problems	O
.	O
</s>
