The struggle for respect in a Planning Centric World…
AI-BASED SCHEDULING
Stephen Smith
Carnegie Mellon University
AI Scheduling – the struggle for
respect …
 1990s – Formation of research community
 The Period of Basic Disconnect
 Int. Conference on AI Planning Systems (AIPS)
 European Conference on Planning (ECP)
 Perspectives:
 There is a restricted class of planning problems
concerned with synchronizing plans in time (mostly
uninteresting from the standpoint of stacking blocks)
 Is scheduling about core techniques or about solving
application problems?
AI Scheduling – the struggle
for respect …
 2000-2002 – Recognition
 AIPS changed its name to Int. Conf. on AI Planning
and Scheduling
 I got a paper accepted in ECP!
 Perspectives
 Increasing recognition that most real planning
problems must worry about situating actions in time
and making good use of scarce resources
 Consideration of integration frameworks
 But majority view of scheduling is really still as a black
box component of a larger planning system
AI Scheduling – the struggle
for respect …
 2003 onward – Age of Acceptance (?)
 Less work in the planning community on inventing
planning techniques to solve scheduling problems
 At ICAPS 2004, we actually held a workshop on how
planning might be used to solve scheduling
subproblems
 More emphasis on common core technologies:
temporal reasoning, search
What is Planning and Scheduling?
 Planning - Synthesis of
 Scheduling - Assignment of
action sequences to achieve
goals (what to do)
preconds
clear(x)
clear(y)
on(x,?)
stack(x,y)
postconds
¬on(x,?)
on(x,y)
clear(?)
preconds
clear(x)
on(x,?)
putdown(x)
postconds
¬on(x,?)
on(x,t)
clear(?)
resources and times to actions to
maximize performance (how and
when)
j
i
OP1,1
on(b,t)
on(g,t)
on(r,g)
clear(b)
clear(r)
on(b,r)
on(g,r)
rd1
OP1,2
R1
st(i) + p(i) ≤ st(j), where p(i)
is the processing time of op i
i
dd1
R2
R
j
st(i) + p(i) ≤ st(j) ∨ st(j) + p(j) ≤ st(i)
rd(j) ≤ st(i) for each op i of job j
rd2
putdown(r)
OP2,1
stack(b,r)
clear(g)
OP1,3
dd2
OP2,2
R1
OP2,1 OP1,2
R2 OP1,1
stack(g,b)
Minimize ∑ |c(j) - dd(j)|
OP2,2 OP1,3
In recent years, the distinction has started to blur:
Scheduling
Planning
resources
durative actions,
temporal reasoning
maximizing # of goals
achieved, # of soft
constraints satisfied
resource setup
and state
constraints
action selection from
pre-computed resource
& process alternatives