12,059 research outputs found
FORM Matters: Fast Symbolic Computation under UNIX
We give a brief introduction to FORM, a symbolic programming language for
massive batch operations, designed by J.A.M. Vermaseren. In particular, we
stress various methods to efficiently use FORM under the UNIX operating system.
Several scripts and examples are given, and suggestions on how to use the vim
editor as development platform.Comment: 10 pages, PDF document (PDFLaTeX source available upon request) with
2 JPG figures; submitted to Computers & Mathematics with Application
Self force on a scalar charge in the spacetime of a stationary, axisymmetric black hole
We study the self force acting on a particle endowed with scalar charge,
which is held static (with respect to an undragged, static observer at
infinity) outside a stationary, axially-symmetric black hole. We find that the
acceleration due to the self force is in the same direction as the black hole's
spin, and diverges when the particle approaches the outer boundary of the black
hole's ergosphere. This acceleration diverges more rapidly approaching the
ergosphere's boundary than the particle's acceleration in the absence of the
self force. At the leading order this self force is a (post)-Newtonian
effect. For scalar charges with high charge-to-mass ratio, the acceleration due
to the self force starts dominating over the regular acceleration already far
from the black hole. The self force is proportional to the rate at which the
black hole's rotational energy is dissipated. This self force is local (i.e.,
only the Abraham-Lorentz-Dirac force and the local coupling to Ricci curvature
contribute to it). The non-local, tail part of the self force is zero.Comment: 28 pages, 9 figure
Combinatorial species and graph enumeration
In enumerative combinatorics, it is often a goal to enumerate both labeled
and unlabeled structures of a given type. The theory of combinatorial species
is a novel toolset which provides a rigorous foundation for dealing with the
distinction between labeled and unlabeled structures. The cycle index series of
a species encodes the labeled and unlabeled enumerative data of that species.
Moreover, by using species operations, we are able to solve for the cycle index
series of one species in terms of other, known cycle indices of other species.
Section 3 is an exposition of species theory and Section 4 is an enumeration of
point-determining bipartite graphs using this toolset. In Section 5, we extend
a result about point-determining graphs to a similar result for
point-determining {\Phi}-graphs, where {\Phi} is a class of graphs with certain
properties. Finally, Appendix A is an expository on species computation using
the software Sage [9] and Appendix B uses Sage to calculate the cycle index
series of point-determining bipartite graphs.Comment: 39 pages, 16 figures, senior comprehensive project at Carleton
Colleg
Towards Assume-Guarantee Profiles for Autonomous Vehicles
Rules or specifications for autonomous vehicles are currently formulated on a case-by-case basis, and put together in a rather ad-hoc fashion. As a step towards eliminating this practice, we propose a systematic procedure for generating a set of supervisory specifications for self-driving cars that are 1) associated with a distributed assume-guarantee structure and 2) characterizable by the notion of consistency and completeness. Besides helping autonomous vehicles make better decisions on the road, the assume-guarantee contract structure also helps address the notion of blame when undesirable events occur. We give several game-theoretic examples to demonstrate applicability of our framework
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