<s>
Phoenix	O
is	O
a	O
decentralized	O
network	O
coordinate	O
(	O
NC	O
)	O
system	O
based	O
on	O
the	O
matrix	B-Application
factorization	I-Application
model	O
.	O
</s>
<s>
Use	O
cases	O
:	O
Vuze	B-Application
BitTorrent	B-Protocol
,	O
application	O
layer	O
multicast	O
,	O
PeerWise	O
overlay	O
,	O
multi-player	O
online	O
gaming	O
.	O
</s>
<s>
Triangle	O
inequality	O
violation	O
(	O
TIV	O
)	O
is	O
widely	O
exist	O
on	O
the	O
Internet	O
due	O
to	O
the	O
current	O
sub-optimal	O
internet	B-Protocol
routing	I-Protocol
.	O
</s>
<s>
Phoenix	O
uses	O
a	O
matrix	B-Application
factorization	I-Application
(	O
MF	O
)	O
model	O
,	O
which	O
does	O
not	O
have	O
the	O
constraint	O
of	O
TIV	O
.	O
</s>
<s>
This	O
matrix	B-Application
factorization	I-Application
is	O
essentially	O
a	O
problem	O
of	O
linear	O
dimensionality	O
reduction	O
and	O
Phoenix	O
tries	O
to	O
solve	O
it	O
in	O
a	O
distributed	O
way	O
.	O
</s>
<s>
For	O
node	O
discovery	O
,	O
Phoenix	O
uses	O
a	O
distributed	O
scheme	O
,	O
so-called	O
peer	O
exchange	O
(	O
PEX	O
)	O
,	O
which	O
is	O
used	O
in	O
BitTorrent	B-Protocol
(	O
protocol	O
)	O
.	O
</s>
