When almost all sets are difference dominated

We investigate the relationship between the sizes of the sum and difference sets attached to a subset of {0,1,...,N}, chosen randomly according to a binomial model with parameter p(N), with N^{-1} = o(p(N)). We show that the random subset is almost surely difference dominated, as N --> oo, for any choice of p(N) tending to zero, thus confirming a conjecture of Martin and O'Bryant. The proofs use recent strong concentration results. Furthermore, we exhibit a threshold phenomenon regarding the ratio of the size of the difference- to the sumset. If p(N) = o(N^{-1/2}) then almost all sums and differences in the random subset are almost surely distinct, and in particular the difference set is almost surely about twice as large as the sumset. If N^{-1/2} = o(p(N)) then both the sum and difference sets almost surely have size (2N+1) - O(p(N)^{-2}), and so the ratio in question is almost surely very close to one. If p(N) = c N^{-1/2} then as c increases from zero to infinity (i.e., as the threshold is crossed), the same ratio almost surely decreases continuously from two to one according to an explicitly given function of c. We also extend our results to the comparison of the generalized difference sets attached to an arbitrary pair of binary linear forms. For certain pairs of forms f and g, we show that there in fact exists a sharp threshold at c_{f,g} N^{-1/2}, for some computable constant c_{f,g}, such that one form almost surely dominates below the threshold, and the other almost surely above it. The heart of our approach involves using different tools to obtain strong concentration of the sizes of the sum and difference sets about their mean values, for various ranges of the parameter p.Comment: Version 2.1. 24 pages. Fixed a few typos, updated reference

Um dilema para teorias naturalistas da intencionalidade

I argue that a dilemma arises for naturalistic philosophers of mind in the naturalised semantics tradition. Giving a naturalistic account of the mind is a pressing problem. Brentano’s Thesis — that a state is mental if, and only if, that state has underived representational content — provides an attractive route to naturalising the mental. If true, Brentano’s Thesis means that naturalising representation is sufficient for naturalising the mental. But a naturalist who accepts Brentano’s Thesis thus commits to an eliminativism about the category of the mental. This is because naturalistic theories of representation are reductive, and so over-generalise by applying to patently non-mental states. According to these theories, it has been argued, phenomena like tree rings and saliva come out as representational. Only proposing further Naturalistic conditions on representation could avoid the eliminativist conclusion. But this shows that Naturalists have made only limited progress towards naturalising the mental. And if a Naturalist rejects Brentano’s Thesis, then she gives up on a clear link between representation and mentality. Hence, it is incumbent on the Naturalist to propose another, naturalistically acceptable, mark of the mental. This, again, shows that Naturalists have made only limited progress on the issue of naturalising the mental.Keywords: Intentionality, representation, physicalism, eliminativism, Brentano, materialism, naturalism.Eu argumento que surge um dilema para os filósofos naturalistas da mente na tradição semântica naturalizada e, assim, dar uma explicação naturalista da mente é uma questão urgente. A Tese de Brentano - de que um estado é mental se, e somente se, esse estado tem conteúdo representacional não derivado - fornece uma rota atraente para naturalizar o mental. Se for verdadeira, a Tese de Brentano significa que naturalizar a representação é suficiente para naturalizar o mental. Mas um naturalista que aceita a Tese de Brentano compromete-se, portanto, com um eliminativismo sobre a categoria do mental. Isso ocorre porque as teorias naturalistas da representação são redutivas e, portanto, generalizam excessivamente, aplicando-se a estados patentemente não mentais. De acordo com essas teorias, argumentou-se, fenômenos como anéis de árvores e saliva contam como representacionais. Somente a proposta de outras condições naturalistas sobre a representação poderia evitar a conclusão eliminativista. Mas isso mostra que os naturalistas fizeram apenas um progresso limitado no sentido de naturalizar o mental. E se um naturalista rejeita a tese de Brentano, então ele abandona uma ligação clara entre representação e mentalidade. Consequentemente, cabe ao naturalista propor uma outra marca do mental, naturalisticamente aceitável. Isso, mais uma vez, mostra que os naturalistas fizeram apenas um progresso limitado na questão da naturalização do mental.Palavras-chave: Intencionalidade, representação, fisicalismo, eliminativismo, Brentano, materialismo, naturalismo

Presence metadata in the Internet of Things challenges and opportunities

The Internet of Things is an emerging computing paradigm that promises to revolutionise society. The widespread capture and aggregation of data from sensors and smart devices combined with processing using machine learning in cloud computing platforms provides unrivalled insights into our environment. In addition to the numerous benefits (smart healthcare, cities, transportation, etc.) such insights potentially jeopardise the privacy of individuals, organisations, and society as whole. This is despite UK and EU regulations attempting to mitigate the risk of individuals’ data exposure and the impact of it on their security. To demonstrate the exploitation of metadata and its threat to privacy, this paper presents Meta-Blue, a Bluetooth Low Energy metadata capture, analysis, and visualisation tool. The results of a case study are combined with an overview of literature on IoT privacy to provide a holistic overview of the challenges and opportunities presented by IoT metadata

Modern Techniques for Discovering Digital Steganography

Digital steganography can be difficult to detect and as such is an ideal way of engaging in covert communications across the Internet. This research paper is a work-in-progress report on instances of steganography that were identified on websites on the Internet including some from the DarkWeb using the application of new methods of deep learning algorithms. This approach to the identification of Least Significant Bit (LSB) Steganography using Convolutional Neural Networks (CNN) has demonstrated some efficiency for image classification. The CNN algorithm was trained using datasets of images with known steganography and then applied to datasets with images to identify concealed data. The algorithm was trained using 5000 clean images and 5000 Steganography images. With the correct configurations made to the deep learning algorithms, positive results were obtained demonstrating a greater speed, accuracy and fewer false positives than the current steganalysis tools

Flight test pilot evaluation of a delayed flap approach procedure

Using NASA's CV-990 aircraft, a delayed flap approach procedure was demonstrated to nine guest pilots from the air transport industry. Four demonstration flights and 37 approaches were conducted under VFR weather conditions. A limited pilot evaluation of the delayed flap procedure was obtained from pilot comments and from questionaires they completed. Pilot acceptability, pilot workload, and ATC compatibility were quantitatively rated. The delayed flap procedure was shown to be feasible, and suggestions for further development work were obtained

Delayed flap approach procedures for noise abatement and fuel conservation

The NASA/Ames Research Center is currently investigating the delayed flap approach during which pilot actions are determined and prescribed by an onboard digital computer. The onboard digital computer determines the proper timing for the deployment of the landing gear and flaps based on the existing winds and airplane gross weight. Advisory commands are displayed to the pilot. The approach is flown along the conventional ILS glide slope but is initiated at a higher airspeed and in a clean aircraft configuration that allows for low thrust and results in reduced noise and fuel consumption. Topics discussed include operational procedures, pilot acceptability of these procedures, and fuel/noise benefits resulting from flight tests and simulation