Model-based Planning in Physical domains using SetGraphs

This paper proposes a non-propositional representation framework for planning in physical domains. Physical planning problems involve identifying a correct sequence (plan) of object manipulations, transformations and spatial rearrangements to achieve an assigned goal. The problem of the ramification of action effects causes most current (propositional) planning languages to have inefficient encodings of physical domains. A simpler and more efficient representation is proposed, in which actions, goals and world state are modelled using ‘setGraphs’. A setGraph is an abstract data-structure able to capture implicitly the structural and topological constraints of a physical domain. Despite being model-based, the representation also allows the use of types and propositional furmulæ to specify additional domain constraints. Experimental results obtained with a specific implementation of the representation indicate significant improvements in performance in all of the domains considered

We Must Choose The Simplest Physical Theory: Levin-Li-Vitányi Theorem And Its Potential Physical Applications

. If several physical theories are consistent with the same experimental data, which theory should we choose? Physicists often choose the simplest theory; this principle (explicitly formulated by Occam) is one of the basic principles of physical reasoning. However, until recently, this principle was mainly a heuristic because it uses the informal notion of simplicity. With the explicit notion of simplicity coming from the Algorithmic Information theory, it is possible not only to formalize this principle in a way that is consistent with its traditional usage in physics, but also to prove this principle, or, to be more precise, deduce it from the fundamentals of mathematical statistics as the choice corresponding to the least informative prior measure. Potential physical applications of this formalization (due to Li and Vit'anyi) are presented. In particular, we show that, on the qualitative level, most fundamental ideas of physics can be re-formulated as natural steps towards choosing..