<s>
Lamport	B-Operating_System
's	I-Operating_System
Distributed	I-Operating_System
Mutual	I-Operating_System
Exclusion	I-Operating_System
Algorithm	I-Operating_System
is	O
a	O
contention-based	O
algorithm	O
for	O
mutual	B-Operating_System
exclusion	I-Operating_System
on	O
a	O
distributed	B-Architecture
system	I-Architecture
.	O
</s>
<s>
The	O
queues	O
are	O
ordered	O
by	O
virtual	O
time	O
stamps	O
derived	O
from	O
Lamport	B-Operating_System
timestamps	I-Operating_System
.	O
</s>
