14,068 research outputs found
Counterexample Guided Inductive Optimization Applied to Mobile Robots Path Planning (Extended Version)
We describe and evaluate a novel optimization-based off-line path planning
algorithm for mobile robots based on the Counterexample-Guided Inductive
Optimization (CEGIO) technique. CEGIO iteratively employs counterexamples
generated from Boolean Satisfiability (SAT) and Satisfiability Modulo Theories
(SMT) solvers, in order to guide the optimization process and to ensure global
optimization. This paper marks the first application of CEGIO for planning
mobile robot path. In particular, CEGIO has been successfully applied to obtain
optimal two-dimensional paths for autonomous mobile robots using off-the-shelf
SAT and SMT solvers.Comment: 7 pages, 14rd Latin American Robotics Symposium (LARS'2017
Antisymmetric tensor propagator with spontaneous Lorentz violation
In this work, we study the spontaneous Lorentz symmetry breaking due to an
antisymmetric 2-tensor field in Minkowski spacetime. For a smooth quadratic
potential, the spectrum of the theory exhibits massless and massive
excitations. We show that the equations of motion for the free field obey some
constraints which lead to the massive mode be non-propagating at leading order.
Besides, there exists a massless mode in the theory which can be identified
with the usual Kalb-Ramond field, carrying only one on-shell degree of freedom.
The same conclusion holds when one analyses the pole structure of its Feynman
propagator. A new complete set of spin-type operators is found, which was the
requirement to evaluate the propagator of the Kalb-Ramond field modified by the
presence of a nonzero vacuum expectation value responsible for the Lorentz
violation.Comment: 13 pages. Some modifications to match published version in
EuroPhysics Letter
Canonical transformation for stiff matter models in quantum cosmology
In the present work we consider Friedmann-Robertson-Walker models in the
presence of a stiff matter perfect fluid and a cosmological constant. We write
the superhamiltonian of these models using the Schutz's variational formalism.
We notice that the resulting superhamiltonians have terms that will lead to
factor ordering ambiguities when they are written as operators. In order to
remove these ambiguities, we introduce appropriate coordinate transformations
and prove that these transformations are canonical using the symplectic method.Comment: Revtex4 Class, 3 pages, No Figure
Germinação de sementes de jacarandá do pará (Dalbergia spruceana Benth.), coletadas em belterra - PA.
Ladder operators for subtle hidden shape invariant potentials
Ladder operators can be constructed for all potentials that present the
integrability condition known as shape invariance, satisfied by most of the
exactly solvable potentials. Using the superalgebra of supersymmetric quantum
mechanics we construct the ladder operators for two exactly solvable potentials
that present a subtle hidden shape invariance.Comment: 9 pages, based on the talk given at International Conference Progress
in Supersymmetric Quantum Mechanics (PSQM03), Valladolid, Spain, 15-19 July,
2003, to appear in a Special Issue of J. Phys. A: Math. Ge
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