<s>
Pegasus	B-Application
is	O
an	O
open-source	O
workflow	B-Operating_System
management	O
system	O
.	O
</s>
<s>
It	O
provides	O
the	O
necessary	O
abstractions	O
for	O
scientists	O
to	O
create	O
scientific	O
workflows	B-Operating_System
and	O
allows	O
for	O
transparent	O
execution	O
of	O
these	O
workflows	B-Operating_System
on	O
a	O
range	O
of	O
computing	O
platforms	O
including	O
high	O
performance	O
computing	O
clusters	O
,	O
clouds	B-Architecture
,	O
and	O
national	O
cyberinfrastructure	O
.	O
</s>
<s>
In	O
Pegasus	B-Application
,	O
workflows	B-Operating_System
are	O
described	O
abstractly	O
as	O
directed	O
acyclic	O
graphs	O
(	O
DAGs	O
)	O
using	O
a	O
provided	O
API	O
for	O
Jupyter	O
Notebooks	O
,	O
Python	B-Language
,	O
R	B-Language
,	O
or	O
Java	B-Language
.	O
</s>
<s>
During	O
execution	O
,	O
Pegasus	B-Application
translates	O
the	O
constructed	O
abstract	O
workflow	B-Operating_System
into	O
an	O
executable	B-Operating_System
workflow	I-Operating_System
which	O
is	O
executed	O
and	O
managed	O
by	O
HTCondor	B-Operating_System
.	O
</s>
<s>
Pegasus	B-Application
is	O
being	O
used	O
in	O
a	O
number	O
of	O
different	O
disciplines	O
including	O
astronomy	O
,	O
gravitational-wave	O
physics	O
,	O
bioinformatics	O
,	O
earthquake	O
engineering	O
,	O
and	O
helioseismology	O
.	O
</s>
<s>
The	O
development	O
of	O
Pegasus	B-Application
started	O
in	O
2001	O
.	O
</s>
