Skip to content

fix(planning): No-op HTN tasks should not contribute to the makespan. #212

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
arbimo wants to merge 1 commit into
base: master
Choose a base branch
from
Open

fix(planning): No-op HTN tasks should not contribute to the makespan. #212

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
21 changes: 18 additions & 3 deletions planning/planners/src/encode.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -518,15 +518,30 @@ pub fn encode(pb: &FiniteProblem, metric: Option<Metric>) -> std::result::Result

for ch in &pb.chronicles {
let prez = ch.chronicle.presence;
use ChronicleKind::*;
// chronicle finishes before the horizon and has a non negative duration
if matches!(ch.chronicle.kind, ChronicleKind::Action | ChronicleKind::DurativeAction) {
if matches!(ch.chronicle.kind, Action | DurativeAction) {
solver.enforce(f_leq(ch.chronicle.end, pb.makespan_ub), [prez]);
}
solver.enforce(f_leq(ch.chronicle.start, ch.chronicle.end), [prez]);
match ch.chronicle.kind {
Problem | Action | DurativeAction => {
solver.enforce(f_leq(ch.chronicle.start, ch.chronicle.end), [prez])
}
Method => {
// Minimum length of a method is -EPSILON (possible if it does not introduce any actions, directly or indirectly).
// This is to ensure that, if a method is empty, the decomposed task can have a -EPSILON duration
solver.enforce(f_leq(ch.chronicle.start - FAtom::EPSILON, ch.chronicle.end), [prez])
}
}

// enforce temporal coherence between the chronicle and its subtasks
for subtask in &ch.chronicle.subtasks {
solver.enforce(f_leq(subtask.start, subtask.end), [prez]);
// a task can have a -EPSILON duration which will only occur when the underlying method does not introduce any action.
// This ensures that a no-op task does not contribute to the makespan :
// A task network constraint `t1 < t2` is translated to `t1.end + epsilon <= t2.start`.
// When `t1` is a no-op and set to its minimal duration, it only requires `t1.start <= t2.start`, meaning that
// `t1` does not reserve any time
solver.enforce(f_leq(subtask.start - FAtom::EPSILON, subtask.end), [prez]);
solver.enforce(f_leq(ch.chronicle.start, subtask.start), [prez]);
solver.enforce(f_leq(subtask.end, ch.chronicle.end), [prez]);
}
Expand Down