254 research outputs found
On the Minimal Revision Problem of Specification Automata
As robots are being integrated into our daily lives, it becomes necessary to
provide guarantees on the safe and provably correct operation. Such guarantees
can be provided using automata theoretic task and mission planning where the
requirements are expressed as temporal logic specifications. However, in
real-life scenarios, it is to be expected that not all user task requirements
can be realized by the robot. In such cases, the robot must provide feedback to
the user on why it cannot accomplish a given task. Moreover, the robot should
indicate what tasks it can accomplish which are as "close" as possible to the
initial user intent. This paper establishes that the latter problem, which is
referred to as the minimal specification revision problem, is NP complete. A
heuristic algorithm is presented that can compute good approximations to the
Minimal Revision Problem (MRP) in polynomial time. The experimental study of
the algorithm demonstrates that in most problem instances the heuristic
algorithm actually returns the optimal solution. Finally, some cases where the
algorithm does not return the optimal solution are presented.Comment: 23 pages, 16 figures, 2 tables, International Joural of Robotics
Research 2014 Major Revision (submitted
Structure, conduct and the stochastic volatility of food markets: theory and empirics
The relationship between price volatility and competition is examined. Atheoretic, vector auto regressions on farm prices of wheat and retail prices of derivatives (flour, bread, pasta, bulgur and cookies) are compared to results from a dynamic, simultaneous-equations model with theory-based farm-to-retail linkages. Analytical results yield insights about numbers of firms and their impacts on demand- and supply-side multipliers, but the applications to Turkish time series (1988:1-1996:12) yield mixed results
The Loop Group of E8 and Targets for Spacetime
The dimensional reduction of the E8 gauge theory in eleven dimensions leads
to a loop bundle in ten dimensional type IA string theory. We show that the
restriction to the Neveu-Schwarz sector leads naturally to a sigma model with
target space E8 with the ten-dimensional spacetime as the source. The
corresponding bundle has a structure group the group of based loops, whose
classifying space we study. We explore some consequences of this proposal such
as possible Lagrangians and existence of flat connections.Comment: 17 pages, main section improved, change in title, reference and
acknowledgement adde
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