<s>
In	O
computer	B-General_Concept
science	I-General_Concept
,	O
empirical	B-General_Concept
algorithmics	I-General_Concept
(	O
or	O
experimental	B-General_Concept
algorithmics	I-General_Concept
)	O
is	O
the	O
practice	O
of	O
using	O
empirical	O
methods	O
to	O
study	O
the	O
behavior	O
of	O
algorithms	O
.	O
</s>
<s>
Methods	O
from	O
empirical	B-General_Concept
algorithmics	I-General_Concept
complement	O
theoretical	O
methods	O
for	O
the	O
analysis	B-General_Concept
of	I-General_Concept
algorithms	I-General_Concept
.	O
</s>
<s>
Through	O
the	O
principled	O
application	O
of	O
empirical	O
methods	O
,	O
particularly	O
from	O
statistics	O
,	O
it	O
is	O
often	O
possible	O
to	O
obtain	O
insights	O
into	O
the	O
behavior	O
of	O
algorithms	O
such	O
as	O
high-performance	O
heuristic	B-Algorithm
algorithms	I-Algorithm
for	O
hard	O
combinatorial	O
problems	O
that	O
are	O
(	O
currently	O
)	O
inaccessible	O
to	O
theoretical	O
analysis	O
.	O
</s>
<s>
Empirical	O
methods	O
can	O
also	O
be	O
used	O
to	O
achieve	O
substantial	O
improvements	O
in	O
algorithmic	B-General_Concept
efficiency	I-General_Concept
.	O
</s>
<s>
American	O
computer	O
scientist	O
Catherine	O
McGeoch	O
identifies	O
two	O
main	O
branches	O
of	O
empirical	B-General_Concept
algorithmics	I-General_Concept
:	O
the	O
first	O
(	O
known	O
as	O
empirical	O
analysis	O
)	O
deals	O
with	O
the	O
analysis	O
and	O
characterization	O
of	O
the	O
behavior	O
of	O
algorithms	O
,	O
and	O
the	O
second	O
(	O
known	O
as	O
algorithm	O
design	O
or	O
algorithm	B-Algorithm
engineering	I-Algorithm
)	O
is	O
focused	O
on	O
empirical	O
methods	O
for	O
improving	O
the	O
performance	O
of	O
algorithms	O
.	O
</s>
<s>
Research	O
in	O
empirical	B-General_Concept
algorithmics	I-General_Concept
is	O
published	O
in	O
several	O
journals	O
,	O
including	O
the	O
(	O
JEA	O
)	O
and	O
the	O
(	O
JAIR	O
)	O
.	O
</s>
<s>
Besides	O
Catherine	O
McGeoch	O
,	O
well-known	O
researchers	O
in	O
empirical	B-General_Concept
algorithmics	I-General_Concept
include	O
Bernard	O
Moret	O
,	O
Giuseppe	O
F	O
.	O
Italiano	O
,	O
Holger	O
H	O
.	O
Hoos	O
,	O
David	O
S	O
.	O
Johnson	O
,	O
and	O
Roberto	O
Battiti	O
.	O
</s>
<s>
In	O
the	O
absence	O
of	O
empirical	B-General_Concept
algorithmics	I-General_Concept
,	O
analyzing	O
the	O
complexity	O
of	O
an	O
algorithm	O
can	O
involve	O
various	O
theoretical	O
methods	O
applicable	O
to	O
various	O
situations	O
in	O
which	O
the	O
algorithm	O
may	O
be	O
used	O
.	O
</s>
<s>
When	O
an	O
individual	O
algorithm	O
is	O
profiled	O
,	O
as	O
with	O
complexity	B-General_Concept
analysis	I-General_Concept
,	O
memory	O
and	O
cache	O
considerations	O
are	O
often	O
more	O
significant	O
than	O
instruction	O
counts	O
or	O
clock	O
cycles	O
;	O
however	O
,	O
the	O
profiler	O
's	O
findings	O
can	O
be	O
considered	O
in	O
light	O
of	O
how	O
the	O
algorithm	O
accesses	O
data	O
rather	O
than	O
the	O
number	O
of	O
instructions	O
it	O
uses	O
.	O
</s>
<s>
Performance	O
profiling	O
has	O
been	O
applied	O
,	O
for	O
example	O
,	O
during	O
the	O
development	O
of	O
algorithms	O
for	O
matching	B-Algorithm
wildcards	I-Algorithm
.	O
</s>
<s>
Early	O
algorithms	O
for	O
matching	B-Algorithm
wildcards	I-Algorithm
,	O
such	O
as	O
Rich	B-Application
Salz	I-Application
 '	O
wildmat	B-Algorithm
algorithm	O
,	O
typically	O
relied	O
on	O
recursion	O
,	O
a	O
technique	O
criticized	O
on	O
grounds	O
of	O
performance	O
.	O
</s>
<s>
The	O
Krauss	B-Algorithm
matching	I-Algorithm
wildcards	I-Algorithm
algorithm	I-Algorithm
was	O
developed	O
based	O
on	O
an	O
attempt	O
to	O
formulate	O
a	O
non-recursive	O
alternative	O
using	O
test	O
cases	O
followed	O
by	O
optimizations	O
suggested	O
via	O
performance	O
profiling	O
,	O
resulting	O
in	O
a	O
new	O
algorithmic	O
strategy	O
conceived	O
in	O
light	O
of	O
the	O
profiling	O
along	O
with	O
other	O
considerations	O
.	O
</s>
<s>
Profilers	O
that	O
collect	O
data	O
at	O
the	O
level	O
of	O
basic	B-Application
blocks	I-Application
or	O
that	O
rely	O
on	O
hardware	O
assistance	O
provide	O
results	O
that	O
can	O
be	O
accurate	O
enough	O
to	O
assist	O
software	O
developers	O
in	O
optimizing	O
algorithms	O
for	O
a	O
particular	O
computer	O
or	O
situation	O
.	O
</s>
