This is the same issue as issue 146, which is now resolved. So I close this one
as well.

> The question is what we should do in these cases. Of course, we can multiply
> out all possible combinations of values.

I would suggest that we don't do this and instead support multiple effects
affecting the same variable properly everywhere we currently support conditional
effects.

> Malte, do you have an idea which parts of the search component rely on the above
> assumption?

No, but most of them don't support conditional effects in any case.

I reimplemented the translation of operators to fix this bug. One problem is
that now the translator can create operators with several conditional effects on
one variable that set the variable to different values (in this case the
conditions are mutually exclusive). Previously the translator simply bailed out
in these cases. The issue is that parts of the search component could rely on
the fact that an operator can set a variable only to one possible new value.

The question is what we should do in these cases. Of course, we can multiply out
all possible combinations of values. However, this could lead to many operators
with lots of preconditions: first, there are exponentially many such
combinations, second, we would need to include negated effect conditions for the
other values as operator precondition and negating a finite domain "atom" V=v
means replacing it with a disjunction over all other values of V.

So I wonder whether this is really the right way to go. Maybe we should rather
use a similar procedure as for axioms and conditional effects, where search
components that do not support them simply raise an exception. 

Malte, do you have an idea which parts of the search component rely on the above
assumption?

Update: This is not connected to the invariant synthesis but to issue 146
(operators that conditionally delete/add the same fact).

This is probably connected to the bug in the invariant synthesis (issue 132).

Waiting for issue 132 to be resolved...

Message from Héctor Geffner:

Hi Malte,

I'm doing some work with Fabio (in the cc) where
we translate some problems into classical ones,
and solve them with lama, ff, etc. As usual.

In the translation, Fabio now generates pddl's
that ff parses well, but lama (and I guess, fd)
doesn't, reporting: 
 
 "Add effect with uncertain del effect partner?"
 AssertionError: Add effect with uncertain del effect partner?

Any idea of what this is?

I'm here from my students that Lama/FD/IPC base planner don't handle
negative preconds all that well, but this doesn't seem to be the problem
(I think I commented them out).

Example pddl files that report the error above
are attached.

Thanks a lot. Best
-hector