<s>
Archetypal	B-Algorithm
analysis	I-Algorithm
in	O
statistics	O
is	O
an	O
unsupervised	B-General_Concept
learning	I-General_Concept
method	O
similar	O
to	O
cluster	B-Algorithm
analysis	I-Algorithm
and	O
introduced	O
by	O
Adele	O
Cutler	O
and	O
Leo	O
Breiman	O
in	O
1994	O
.	O
</s>
<s>
Rather	O
than	O
"	O
typical	O
"	O
observations	O
(	O
cluster	O
centers	O
)	O
,	O
it	O
seeks	O
extremal	O
points	O
in	O
the	O
multidimensional	O
data	O
,	O
the	O
"	O
archetypes	B-Language
"	O
.	O
</s>
<s>
The	O
archetypes	B-Language
are	O
convex	O
combinations	O
of	O
observations	O
chosen	O
so	O
that	O
observations	O
can	O
be	O
approximated	O
by	O
convex	O
combinations	O
of	O
the	O
archetypes	B-Language
.	O
</s>
<s>
Archetypal	B-Algorithm
analysis	I-Algorithm
.	O
</s>
<s>
Anil	O
Damle	O
,	O
Yuekai	O
Sun	O
:	O
A	O
geometric	O
approach	O
to	O
archetypal	B-Algorithm
analysis	I-Algorithm
and	O
non-negative	O
matrix	O
factorization	O
.	O
</s>
