Title Determine unsolvability based on landmark graph
Priority feature Status chatting
Superseder Nosy List clemens, jendrik, malte, salome, silvan, thomas
Assigned To Keywords
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Created on 2021-02-18.12:51:10 by thomas, last changed by thomas.

msg10089 (view) Author: thomas Date: 2021-02-18.12:51:09
The structure of the landmark graph can reveal that a planning task is unsolvable, e.g. if:

1. there is a landmark with an empty set of first achievers that is not satisfied in the initial state;
2. there is a cycle in the landmark graph that consists only of natural orderings.

The first of these is currently checked in every state, and the second is not checked at all. In this issue, we'd like to 

i. enhance landmark factories with a method that determines if a planning task is unsolvable;
ii. make sure that method is used correctly; and
iii. move the per-state check described in 1. into the factories

Further enhancements in this direction that could be part of this issue or not include:
iv. premature termination of the landmark creation because one component already shows unsolvability
v. methods like 2. described above
Date User Action Args
2021-02-18 12:51:10thomascreate