509 research outputs found
Educating Seth: An Ecosophical Conversation
Most accounts of human activity have a particular structure that supports the accounting. Education as a human activity has over centuries, and particularly in the past century, developed a narrative structure that, while seemingly "neutral", privileges accounts of a certain kind. The authors suggest that if ecosophical education is to find a presence in today's schools, the now dominant narrative structure needs to be challenged. By revealing an alternate narrative structure embodied in the particularities of a grade 4 classroom, the authors hope that such a narrative structure can provide ecosophical education with an authentic home in today's schools
On the Quantum Chromatic Numbers of Small Graphs
We make two contributions pertaining to the study of the quantum chromatic
numbers of small graphs. Firstly, in an elegant paper, Man\v{c}inska and
Roberson [\textit{Baltic Journal on Modern Computing}, 4(4), 846-859, 2016]
gave an example of a graph on 14 vertices with quantum chromatic
number 4 and classical chromatic number 5, and conjectured that this is the
smallest graph exhibiting a separation between the two parameters. We describe
a computer-assisted proof of this conjecture, thereby resolving a longstanding
open problem in quantum graph theory. Our second contribution pertains to the
study of the rank- quantum chromatic numbers. While it can now be shown that
for every , and are distinct, few small examples of
separations between these parameters are known. We give the smallest known
example of such a separation in the form of a graph on 21 vertices
with and . The previous record was held by a
graph on 57 vertices that was first considered in the aforementioned
paper of Man\v{c}inska and Roberson and which satisfies
and . In addition, provides the first
provable separation between the parameters and .
We believe that our techniques for constructing and lower bounding its
orthogonal rank could be of independent interest
Innovative Applications of Genetic Algorithms to Problems in Accelerator Physics
The genetic algorithm (GA) is a powerful technique that implements the principles nature uses in biological evolution to optimize a multidimensional nonlinear problem. The GA works especially well for problems with a large number of local extrema, where traditional methods (such as conjugate gradient, steepest descent, and others) fail or, at best, underperform. The field of accelerator physics, among others, abounds with problems which lend themselves to optimization via GAs. In this paper, we report on the successful application of GAs in several problems related to the existing Continuous Electron Beam Accelerator Facility nuclear physics machine, the proposed Medium-energy Electron-Ion Collider at Jefferson Lab, and a radio frequency gun-based injector. These encouraging results are a step forward in optimizing accelerator design and provide an impetus for application of GAs to other problems in the field. To that end, we discuss the details of the GAs used, include a newly devised enhancement which leads to improved convergence to the optimum, and make recommendations for future GA developments and accelerator applications
Certificates for decision problems in temporal logic using context-based tableaux and sequent calculi.
115 p.Esta tesis trata de resolver problemas de Satisfactibilidad y Model Checking, aportando certificados del resultado. En ella, se trabaja con tres lĂłgicas temporales: Propositional Linear Temporal Logic (PLTL), Computation Tree Logic (CTL) y Extended Computation Tree Logic (ECTL). Primero se presenta el trabajo realizado sobre Certified Satisfiability. AhĂ se muestra una adaptaciĂłn del ya existente mĂ©todo dual de tableaux y secuentes basados en contexto para satisfactibilidad de fĂłrmulas PLTL en Negation Normal Form. Se ha trabajado la generaciĂłn de certificados en el caso en el que las fĂłrmulas son insactisfactibles. Por Ăşltimo, se aporta una prueba de soundness del mĂ©todo. Segundo, se ha optimizado con Sat Solvers el mĂ©todo de Certified Satisfiability para el contexto de Certified Model Checking. Se aportan varios ejemplos de sistemas y propiedades. Tercero, se ha creado un nuevo mĂ©todo dual de tableaux y secuentes basados en contexto para realizar Certified Satisfiability para fĂłrmulas CTL yECTL. Se presenta el mĂ©todo y un algoritmo que genera tanto el modelo en el caso de que las fĂłrmulas son satisfactibles como la prueba en el caso en que no lo sean. Por Ăşltimo, se presenta una implementaciĂłn del mĂ©todo para CTL y una experimentaciĂłn comparando el mĂ©todo propuesto con otro mĂ©todo de similares caracterĂsticas
Certifying Correctness for Combinatorial Algorithms : by Using Pseudo-Boolean Reasoning
Over the last decades, dramatic improvements in combinatorialoptimisation algorithms have significantly impacted artificialintelligence, operations research, and other areas. These advances,however, are achieved through highly sophisticated algorithms that aredifficult to verify and prone to implementation errors that can causeincorrect results. A promising approach to detect wrong results is touse certifying algorithms that produce not only the desired output butalso a certificate or proof of correctness of the output. An externaltool can then verify the proof to determine that the given answer isvalid. In the Boolean satisfiability (SAT) community, this concept iswell established in the form of proof logging, which has become thestandard solution for generating trustworthy outputs. The problem isthat there are still some SAT solving techniques for which prooflogging is challenging and not yet used in practice. Additionally,there are many formalisms more expressive than SAT, such as constraintprogramming, various graph problems and maximum satisfiability(MaxSAT), for which efficient proof logging is out of reach forstate-of-the-art techniques.This work develops a new proof system building on the cutting planesproof system and operating on pseudo-Boolean constraints (0-1 linearinequalities). We explain how such machine-verifiable proofs can becreated for various problems, including parity reasoning, symmetry anddominance breaking, constraint programming, subgraph isomorphism andmaximum common subgraph problems, and pseudo-Boolean problems. Weimplement and evaluate the resulting algorithms and a verifier for theproof format, demonstrating that the approach is practical for a widerange of problems. We are optimistic that the proposed proof system issuitable for designing certifying variants of algorithms inpseudo-Boolean optimisation, MaxSAT and beyond
“Hawkeye Supercut."
Read and appreciated by a horde of fans before me, Hawkeye—written by Matt Fraction and often drawn by David Aja—is worth our attention. Marvel released Hawkeye #1 in October 2012, and to date 21 issues have appeared, with most of these collected into three trade paperbacks, My Life as a Weapon (2013), Little Hits (2013) and L.A. Woman (2014). Although individual issues sometimes tell self-contained stories, the series as a whole is unified by its low-key aesthetic: a text page at the beginning of these comics reads, “Clint Barton, a.k.a. Hawkeye, became the greatest sharpshooter known to man. He then joined the Avengers. This is what he does when he’s not being an Avenger.” Clint’s days off are still busy: he mentors a young superhero archer named Kate Bishop (she’s almost as much the main character as Clint), and antagonizes Eastern-European mobsters trying to chase everyone out of the New York City tenement where he lives. The clash between Hawkeye and the mobsters (nicknamed the Tracksuit Draculas) escalates to a deadly siege by the end of the Fraction-Aja run. Hawkeye #22, due July 15th, will bring this arc to a close
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