<s>
A	O
schedule	B-General_Concept
or	O
a	O
timetable	B-Algorithm
,	O
as	O
a	O
basic	O
time-management	O
tool	O
,	O
consists	O
of	O
a	O
list	O
of	O
times	O
at	O
which	O
possible	O
tasks	O
,	O
events	O
,	O
or	O
actions	O
are	O
intended	O
to	O
take	O
place	O
,	O
or	O
of	O
a	O
sequence	O
of	O
events	O
in	O
the	O
chronological	O
order	O
in	O
which	O
such	O
things	O
are	O
intended	O
to	O
take	O
place	O
.	O
</s>
<s>
The	O
process	O
of	O
creating	O
a	O
schedule	B-General_Concept
—	O
deciding	O
how	O
to	O
order	O
these	O
tasks	O
and	O
how	O
to	O
commit	O
resources	O
between	O
the	O
variety	O
of	O
possible	O
tasks	O
—	O
is	O
called	O
scheduling	B-Algorithm
,	O
and	O
a	O
person	O
responsible	O
for	O
making	O
a	O
particular	O
schedule	B-General_Concept
may	O
be	O
called	O
a	O
scheduler	B-Algorithm
.	O
</s>
<s>
Making	O
and	O
following	O
schedules	B-Algorithm
is	O
an	O
ancient	O
human	O
activity	O
.	O
</s>
<s>
Schedules	B-Algorithm
are	O
necessary	O
,	O
or	O
at	O
least	O
useful	O
,	O
in	O
situations	O
where	O
individuals	O
need	O
to	O
know	O
what	O
time	O
they	O
must	O
be	O
at	O
a	O
specific	O
location	O
to	O
receive	O
a	O
specific	O
service	O
,	O
and	O
where	O
people	O
need	O
to	O
accomplish	O
a	O
set	O
of	O
goals	O
within	O
a	O
set	O
time	O
period	O
.	O
</s>
<s>
Schedules	B-Algorithm
can	O
usefully	O
span	O
both	O
short	O
periods	O
,	O
such	O
as	O
a	O
daily	O
or	O
weekly	O
schedule	B-General_Concept
,	O
and	O
long-term	O
planning	O
with	O
respect	O
to	O
periods	O
of	O
several	O
months	O
or	O
years	O
.	O
</s>
<s>
They	O
are	O
often	O
made	O
using	O
a	O
calendar	B-Application
,	O
where	O
the	O
person	O
making	O
the	O
schedule	B-General_Concept
can	O
note	O
the	O
dates	O
and	O
times	O
at	O
which	O
various	O
events	O
are	O
planned	O
to	O
occur	O
.	O
</s>
<s>
Schedules	B-Algorithm
that	O
do	O
not	O
set	O
forth	O
specific	O
times	O
for	O
events	O
to	O
occur	O
may	O
instead	O
list	O
algorithmically	O
an	O
expected	O
order	O
in	O
which	O
events	O
either	O
can	O
or	O
must	O
take	O
place	O
.	O
</s>
<s>
In	O
some	O
situations	O
,	O
schedules	B-Algorithm
can	O
be	O
uncertain	O
,	O
such	O
as	O
where	O
the	O
conduct	O
of	O
daily	O
life	O
relies	O
on	O
environmental	O
factors	O
outside	O
human	O
control	O
.	O
</s>
<s>
People	O
who	O
are	O
vacationing	O
or	O
otherwise	O
seeking	O
to	O
reduce	O
stress	O
and	O
achieve	O
relaxation	O
may	O
intentionally	O
avoid	O
having	O
a	O
schedule	B-General_Concept
for	O
a	O
certain	O
period	O
of	O
time	O
.	O
</s>
<s>
Certain	O
kinds	O
of	O
schedules	B-Algorithm
reflect	O
information	O
that	O
is	O
generally	O
made	O
available	O
to	O
the	O
public	O
,	O
so	O
that	O
members	O
of	O
the	O
public	O
can	O
plan	O
certain	O
activities	O
around	O
them	O
.	O
</s>
<s>
Transportation	O
schedules	B-Algorithm
,	O
such	O
as	O
airline	O
timetables	B-Algorithm
,	O
train	O
schedules	B-Algorithm
,	O
bus	O
schedules	B-Algorithm
,	O
and	O
various	O
public	O
transport	O
timetables	B-Algorithm
are	O
published	O
to	O
allow	O
commuters	O
to	O
plan	O
their	O
travels	O
.	O
</s>
<s>
From	O
the	O
perspective	O
of	O
the	O
organization	O
responsible	O
for	O
making	O
transportation	O
available	O
,	O
schedules	B-Algorithm
must	O
provide	O
for	O
the	O
possibility	O
of	O
schedule	B-General_Concept
delay	O
,	O
a	O
term	O
in	O
transport	O
modeling	O
which	O
refers	O
to	O
a	O
difference	O
between	O
a	O
desired	O
time	O
of	O
arrival	O
or	O
departure	O
and	O
the	O
actual	O
time	O
.	O
</s>
<s>
Concerts	O
and	O
sporting	O
events	O
are	O
typically	O
scheduled	B-Algorithm
so	O
that	O
fans	O
can	O
plan	O
to	O
buy	O
tickets	O
and	O
attend	O
the	O
events	O
.	O
</s>
<s>
An	O
internal	O
schedule	B-General_Concept
is	O
a	O
schedule	B-General_Concept
that	O
is	O
only	O
of	O
importance	O
to	O
the	O
people	O
who	O
must	O
directly	O
abide	O
by	O
it	O
.	O
</s>
<s>
It	O
has	O
been	O
noted	O
that	O
"	O
groups	O
often	O
begin	O
with	O
a	O
schedule	B-General_Concept
imposed	O
from	O
the	O
outside	O
,	O
but	O
effective	O
groups	O
also	O
develop	O
an	O
internal	O
schedule	B-General_Concept
that	O
sets	O
goals	O
for	O
the	O
completion	O
of	O
micro-tasks	O
"	O
.	O
</s>
<s>
Unlike	O
schedules	B-Algorithm
for	O
public	O
events	O
or	O
publicly	O
available	O
amenities	O
,	O
there	O
is	O
no	O
need	O
to	O
go	O
to	O
the	O
time	O
and	O
effort	O
of	O
publicizing	O
the	O
internal	O
schedule	B-General_Concept
.	O
</s>
<s>
To	O
the	O
contrary	O
,	O
an	O
internal	O
schedule	B-General_Concept
may	O
be	O
kept	O
confidential	O
as	O
a	O
matter	O
of	O
security	O
or	O
propriety	O
.	O
</s>
<s>
An	O
example	O
of	O
an	O
internal	O
schedule	B-General_Concept
is	O
a	O
workplace	O
schedule	B-General_Concept
,	O
which	O
lists	O
the	O
hours	O
that	O
specific	O
employees	O
are	O
expected	O
to	O
be	O
in	O
a	O
workplace	O
,	O
ensure	O
sufficient	O
staffing	O
at	O
all	O
times	O
while	O
in	O
some	O
instances	O
avoiding	O
overstaffing	O
.	O
</s>
<s>
A	O
work	B-Algorithm
schedule	I-Algorithm
for	O
a	O
business	O
that	O
is	O
open	O
to	O
the	O
public	O
must	O
correspond	O
to	O
the	O
hours	O
of	O
operation	O
of	O
the	O
business	O
,	O
so	O
that	O
employees	O
are	O
available	O
at	O
times	O
when	O
customers	O
are	O
able	O
to	O
use	O
the	O
services	O
of	O
the	O
business	O
.	O
</s>
<s>
One	O
common	O
method	O
of	O
scheduling	B-Algorithm
employees	O
to	O
ensure	O
the	O
availability	O
of	O
appropriate	O
resources	O
is	O
a	O
Gantt	B-Application
chart	I-Application
.	O
</s>
<s>
Another	O
example	O
of	O
an	O
internal	O
schedule	B-General_Concept
is	O
the	O
class	O
schedule	B-General_Concept
of	O
an	O
individual	O
student	O
,	O
indicating	O
what	O
days	O
and	O
times	O
their	O
classes	O
will	O
be	O
held	O
.	O
</s>
<s>
A	O
schedule	B-General_Concept
may	O
also	O
involve	O
the	O
completion	O
of	O
a	O
project	O
with	O
which	O
the	O
public	O
has	O
no	O
interaction	O
public	O
prior	O
to	O
its	O
completion	O
.	O
</s>
<s>
In	O
project	O
management	O
,	O
a	O
formal	O
schedule	B-General_Concept
will	O
often	O
be	O
created	O
as	O
an	O
initial	O
step	O
in	O
carrying	O
out	O
a	O
specific	O
project	O
,	O
such	O
as	O
the	O
construction	O
of	O
a	O
building	O
,	O
development	O
of	O
a	O
product	O
,	O
or	O
launch	O
of	O
a	O
program	O
.	O
</s>
<s>
Establishing	O
a	O
project	O
management	O
schedule	B-General_Concept
involves	O
listing	O
milestones	O
,	O
activities	O
,	O
and	O
deliverables	O
with	O
intended	O
start	O
and	O
finish	O
dates	O
,	O
of	O
which	O
the	O
scheduling	B-Algorithm
of	O
employees	O
may	O
be	O
an	O
element	O
.	O
</s>
<s>
A	O
production	B-Application
process	I-Application
schedule	I-Application
is	O
used	O
for	O
the	O
planning	O
of	O
the	O
production	O
or	O
the	O
operation	O
,	O
while	O
a	O
resource	B-Algorithm
schedule	I-Algorithm
aids	O
in	O
the	O
logistical	O
planning	O
for	O
sharing	O
resources	O
among	O
several	O
entities	O
.	O
</s>
<s>
In	O
such	O
cases	O
,	O
a	O
schedule	B-General_Concept
"	O
is	O
obtained	O
by	O
estimating	O
the	O
duration	O
of	O
each	O
task	O
and	O
noting	O
any	O
dependencies	O
amongst	O
those	O
tasks	O
"	O
.	O
</s>
<s>
Scheduling	B-Algorithm
of	O
projects	O
,	O
therefore	O
,	O
requires	O
the	O
identification	O
of	O
all	O
of	O
the	O
tasks	O
necessary	O
to	O
complete	O
the	O
project	O
,	O
and	O
the	O
earliest	O
time	O
at	O
which	O
each	O
task	O
can	O
be	O
completed	O
.	O
</s>
<s>
In	O
creating	O
a	O
schedule	B-General_Concept
,	O
a	O
certain	O
amount	O
of	O
time	O
is	O
usually	O
set	O
aside	O
as	O
a	O
contingency	O
against	O
unforeseen	O
days	O
.	O
</s>
<s>
This	O
time	O
is	O
called	O
scheduling	B-Algorithm
variance	O
,	O
or	O
float	O
,	O
and	O
is	O
a	O
core	O
concept	O
for	O
the	O
critical	O
path	O
method	O
.	O
</s>
<s>
Scheduling	B-Algorithm
is	O
important	O
as	O
an	O
internal	O
process	O
in	O
computer	B-General_Concept
science	I-General_Concept
,	O
wherein	O
a	O
schedule	B-General_Concept
is	O
a	O
list	O
of	O
actions	O
from	O
a	O
set	O
of	O
transactions	O
in	O
databases	O
,	O
and	O
scheduling	B-Algorithm
is	O
the	O
way	O
various	O
processes	O
are	O
assigned	O
in	O
computer	B-Operating_System
multitasking	I-Operating_System
and	O
multiprocessing	O
operating	O
system	O
design	O
.	O
</s>
<s>
This	O
kind	O
of	O
scheduling	B-Algorithm
is	O
incorporated	O
into	O
the	O
computer	O
program	O
,	O
and	O
the	O
user	O
may	O
be	O
completely	O
unaware	O
of	O
what	O
tasks	O
are	O
being	O
carried	O
out	O
and	O
when	O
.	O
</s>
<s>
Scheduling	B-Algorithm
operations	O
and	O
issues	O
in	O
computing	O
may	O
include	O
:	O
</s>
<s>
The	O
operation	O
of	O
a	O
network	B-Application
scheduler	I-Application
or	O
packet	B-Application
scheduler	I-Application
,	O
an	O
arbiter	O
program	O
that	O
manages	O
the	O
movement	O
of	O
certain	O
pieces	O
of	O
information	O
in	O
the	O
computer	O
.	O
</s>
<s>
Open-shop	B-Algorithm
scheduling	I-Algorithm
,	O
Job	B-Algorithm
Shop	I-Algorithm
Scheduling	I-Algorithm
,	O
Flow	B-Algorithm
Shop	I-Algorithm
Scheduling	I-Algorithm
Problem	I-Algorithm
,	O
optimization	O
problems	O
in	O
computer	B-General_Concept
science	I-General_Concept
.	O
</s>
<s>
I/O	B-General_Concept
scheduling	I-General_Concept
,	O
the	O
order	O
in	O
which	O
I/O	O
requests	O
are	O
submitted	O
to	O
a	O
block	O
device	O
in	O
operating	O
systems	O
.	O
</s>
<s>
Job	B-General_Concept
scheduler	I-General_Concept
,	O
an	O
enterprise	O
software	O
application	O
in	O
charge	O
of	O
unattended	O
background	O
executions	O
.	O
</s>
<s>
Wireless	B-General_Concept
networks	I-General_Concept
should	O
have	O
a	O
flexible	O
service	O
architecture	O
to	O
integrate	O
different	O
types	O
of	O
services	O
on	O
a	O
single	O
air-interface	O
because	O
terminals	O
have	O
different	O
service	O
requirements	O
.	O
</s>
<s>
Therefore	O
,	O
wireless	O
resources	O
need	O
to	O
be	O
shared	O
among	O
all	O
terminals	O
carefully	O
and	O
it	O
is	O
desirable	O
to	O
schedule	B-General_Concept
the	O
usage	O
of	O
wireless	O
resources	O
as	O
efficiently	O
as	O
possible	O
,	O
while	O
maximizing	O
the	O
overall	O
network	O
performance	O
.	O
</s>
<s>
The	O
scheduling	B-Algorithm
of	O
resources	O
,	O
usually	O
subject	O
to	O
constraints	O
,	O
is	O
the	O
subject	O
of	O
several	O
problems	O
that	O
are	O
in	O
the	O
area	O
of	O
research	O
known	O
as	O
operations	O
research	O
,	O
usually	O
in	O
terms	O
of	O
finding	O
an	O
optimal	O
solution	O
or	O
method	O
for	O
solving	O
.	O
</s>
<s>
For	O
example	O
,	O
the	O
nurse	B-Application
scheduling	I-Application
problem	I-Application
is	O
concerned	O
with	O
scheduling	B-Algorithm
a	O
number	O
of	O
employees	O
with	O
typical	O
constraints	O
such	O
as	O
rotation	O
of	O
shifts	O
,	O
limits	O
on	O
overtime	O
,	O
etc	O
.	O
</s>
<s>
The	O
travelling	B-Algorithm
salesman	I-Algorithm
problem	I-Algorithm
is	O
concerned	O
with	O
scheduling	B-Algorithm
a	O
series	O
of	O
journeys	O
to	O
minimize	O
time	O
or	O
distance	O
.	O
</s>
<s>
Some	O
of	O
these	O
problems	O
may	O
be	O
solved	O
efficiently	O
with	O
linear	B-Algorithm
programming	I-Algorithm
,	O
but	O
many	O
scheduling	B-Algorithm
problems	O
require	O
integer	O
variables	O
.	O
</s>
<s>
Although	O
efficient	O
algorithms	O
exist	O
to	O
give	O
integer	O
solutions	O
in	O
some	O
situations	O
(	O
see	O
network	B-Algorithm
flow	I-Algorithm
models	O
)	O
,	O
most	O
problems	O
that	O
require	O
integer	O
solutions	O
cannot	O
yet	O
be	O
solved	O
efficiently	O
.	O
</s>
<s>
Scheduling	B-Algorithm
is	O
useful	O
in	O
transportation	O
planning	O
.	O
</s>
<s>
The	O
important	O
components	O
of	O
transportation	O
improvement	O
proposals	O
include	O
(	O
a	O
)	O
comprehensive	O
evaluations	O
of	O
the	O
scope	O
of	O
work	O
to	O
be	O
completed	O
,	O
(	O
b	O
)	O
reasonably	O
accurate	O
cost	O
estimates	O
for	O
finishing	O
the	O
task	O
,	O
and	O
(	O
c	O
)	O
a	O
feasible	O
project	O
schedule	B-General_Concept
.	O
</s>
<s>
Poor	O
scoping	O
and/or	O
scheduling	B-Algorithm
may	O
result	O
in	O
serious	O
budget	O
problems	O
,	O
delays	O
and	O
cancellations	O
of	O
transportation	O
improvements	O
,	O
and	O
sometimes	O
even	O
a	O
domino	O
effect	O
that	O
can	O
negatively	O
impact	O
the	O
entire	O
area	O
's	O
transportation	O
planning	O
.	O
</s>
<s>
In	O
an	O
educational	O
institution	O
,	O
a	O
timetable	B-Algorithm
must	O
be	O
established	O
that	O
refers	O
students	O
and	O
teachers	O
to	O
classrooms	O
each	O
hour	O
.	O
</s>
<s>
The	O
challenge	O
of	O
constructing	O
this	O
schedule	B-General_Concept
for	O
larger	O
institutions	O
was	O
addressed	O
by	O
Gunther	O
Schmidt	O
and	O
Thomas	O
Ströhlein	O
in	O
1976	O
.	O
</s>
<s>
They	O
formalized	O
the	O
timetable	B-Algorithm
construction	O
problem	O
,	O
and	O
indicated	O
an	O
iterative	O
process	O
using	O
logical	B-Algorithm
matrices	I-Algorithm
and	O
hypergraphs	O
to	O
obtain	O
a	O
solution	O
.	O
</s>
