Issue1006

Title Uncaught negation in goal
Priority bug Status resolved
Superseder Nosy List gabi, jendrik, malte, pgj
Assigned To Keywords
Optional summary
In the attached problems (q3.pddl and q14.pddl) there is a negation in
the goal formula which is not correctly handled.

The tool reports solution found with a zero-length plan - even though
this does not hold.

q3.pddl demonstrates this by having the following trivially
unsatisfiable goal:

(:goal
(and (not (p17)) (p17))
)

I believe an adequate fix would be to throw an error (as you do in some
other cases when negated clauses are part of the goal).

Created on 2021-02-09.10:23:29 by pgj, last changed by gabi.

Summary
In the attached problems (q3.pddl and q14.pddl) there is a negation in
the goal formula which is not correctly handled.

The tool reports solution found with a zero-length plan - even though
this does not hold.

q3.pddl demonstrates this by having the following trivially
unsatisfiable goal:

(:goal
(and (not (p17)) (p17))
)

I believe an adequate fix would be to throw an error (as you do in some
other cases when negated clauses are part of the goal).
Files
File name Uploaded Type Edit Remove
wrong.zip pgj, 2021-02-09.10:25:03 application/zip
Messages
msg11580 (view) Author: gabi Date: 2024-02-08.21:39:36
This seems to be resolved by issue1055 and I cannot reproduce it anymore. I suggest to close this as solved.
msg10011 (view) Author: malte Date: 2021-02-09.12:35:51
I can reproduce the bug. The translator incorrectly simplifies the goal to an empty goal. Here is a minimal example that demonstrates the bug:

domain file:
========================================================================
(define (domain issue1006-test)
(:requirements :strips :negative-preconditions)
(:predicates (p))
)
========================================================================

problem file:
========================================================================
(define (problem issue1006-test)
(:domain issue1006-test)
(:init (p))
(:goal (and (not (p)) (p)))
)
========================================================================
msg10010 (view) Author: malte Date: 2021-02-09.12:23:34
Thank you, pgj, we will have a look. I have added you to the "nosy list" of this issue, which means that will you be notified of updates related to this issue. If you are not interested in this, please let me know of just remove your name from the nosy list.

Unsolvable tasks are not really invalid inputs; the given goal is well-formed, it is just impossible to reach. So the correct behaviour should be to report the task as unsolvable.
History
Date User Action Args
2024-02-09 14:36:16gabisetstatus: chatting -> resolved
2024-02-08 21:39:36gabisetnosy: + gabi
messages: + msg11580
2021-02-09 12:35:51maltesetmessages: + msg10011
2021-02-09 12:23:34maltesetstatus: unread -> chatting
nosy: + malte, jendrik, pgj
messages: + msg10010
2021-02-09 10:25:03pgjsetfiles: + wrong.zip
2021-02-09 10:23:29pgjcreate