Commit 121aec56 authored by Markus Klinik's avatar Markus Klinik
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say why we assume planning and scheduling are distinct

parent 5b584f37
......@@ -15,7 +15,7 @@ A \emph{scheduler} has the responsibility of finding a schedule given an instanc
In the literature on automated planning and scheduling, for example \citet{Ghallab2004}, planning and scheduling are treated as two distinct problems that can be solved in isolation.
Planning takes as input a start state, a set of state transforming actions, and a goal predicate.
The purpose of planning is to chain actions together to transform the start state into a state that satisfies the goal predicate, via a series of intermediate states.
The purpose of planning is to choose actions and chain them together to transform the start state into a state that satisfies the goal predicate, via a series of intermediate states.
Such a chain of actions is called a \emph{plan}.
Planning is only concerned with the effects of actions on the state, but not with who should execute them and when.
......@@ -32,7 +32,7 @@ For some actions the order in which they are executed does not matter.
Scheduling works best if it gets as input a partial order, so that the scheduler has some freedom to rearrange and parallelize tasks.
Planning in which the output is a partial order instead of a total order is called \emph{partial order planning}, and is an active field of research, see for example the work by \citet{MuiseBM2016}.
For this paper, we assume that a partial order of tasks is given.
For this paper, we assume that a partial order of tasks is given, regardless of how it is obtained.
\paragraph{Second}
There are situations in which the decision \emph{who} executes a task influences \emph{which} other tasks must be executed.
......@@ -41,9 +41,11 @@ This contradicts the assumption that planning and scheduling can be clearly sepa
This arises typically in situations where a resource has to be prepared in order to be used.
For example, when there is a helicopter and a boat for a mission, then choosing one might require different preparation tasks, or a different approach to the mission altogether.
In other words, the mission can not be planned before a resource is chosen.
In other words, the mission can not be planned before a resource is selected.
For this paper, we make the assumption that planning and scheduling can be separated.
Taking such situations into account would complicate our algorithm substantially, leading too far away from our current goal of scheduling resources.
We therefore make the assumption that planning and scheduling \emph{can} be separated.
It is left to the users of our system to model their problems in such a way that resource selection does not influence planning.
See \cref{sec:example-search-and-rescue} for an example.
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