<s>
A	O
prefix	B-Algorithm
hash	I-Algorithm
tree	I-Algorithm
(	O
PHT	O
)	O
is	O
a	O
distributed	O
data	B-General_Concept
structure	I-General_Concept
that	O
enables	O
more	O
sophisticated	O
queries	O
over	O
a	O
distributed	B-Operating_System
hash	I-Operating_System
table	I-Operating_System
(	O
DHT	O
)	O
.	O
</s>
<s>
The	O
prefix	B-Algorithm
hash	I-Algorithm
tree	I-Algorithm
uses	O
the	O
lookup	O
interface	O
of	O
a	O
DHT	O
to	O
construct	O
a	O
trie-based	O
data	B-General_Concept
structure	I-General_Concept
that	O
is	O
both	O
efficient	O
(	O
updates	O
are	O
doubly	O
logarithmic	O
in	O
the	O
size	O
of	O
the	O
domain	O
being	O
indexed	O
)	O
,	O
and	O
resilient	O
(	O
the	O
failure	O
of	O
any	O
given	O
node	O
in	O
a	O
prefix	B-Algorithm
hash	I-Algorithm
tree	I-Algorithm
does	O
not	O
affect	O
the	O
availability	O
of	O
data	O
stored	O
at	O
other	O
nodes	O
)	O
.	O
</s>
