|   | CMU-CS-99-114 Computer Science Department
 School of Computer Science, Carnegie Mellon University
 
    
     
 CMU-CS-99-114
 
Iterative Macro-Operators Revisited:Applying Program Synthesis to Learning in Planning
 
Ute Schmid 
March 1999  
CMU-CS-99-114.psCMU-CS-99-114.pdf
 Keywords: Macro generation, planning, inductive program
synthesis
 The goal of this paper is to demonstrate that a method for 
inductive program synthesis (as described in Schmid & Wysotzki 1998) can
be applied to the problem of learning cyclic (iterative/recursive) 
macro-operations from planning. Input in the program synthesis system 
is a so-called initial program which represents an ordered set of
straight-forward transformations from input states to the desired output. 
In the context of planning, the input states correspond to initial 
states, the output state to the planning goal, and transformations are 
shortest operation sequences. Ordering of transformations can be 
achieved by calculating a minimal spanning tree for the problem graph 
with the state(s) fulfilling the goal as root. We have implemented a 
non-linear backward planner which generates such a complete
partial order as a by-product of planning. Output of the program
synthesis system is a recursive program scheme representing the 
generalization of a program limited to solving a finite problem of 
given size to a general solution strategy. Our synthesis method is 
embedded in the theory of the semantic of functional programs and in 
the theory of inductive inference (see Muehlpfordt & Schmid 1998) and 
thereby provides a sound formal basis for macro-construction. The 
current implementation can generalize tail, linear and tree recursive 
structures and combinations of such structures with multiple
(and possibly interdependent) recursive parameters.
89 pages
 
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