8,353 research outputs found

    Phenomenological Actualism. A Husserlian Metaphysics of Modality?

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    Considering the importance of possible-world semantics for modal logic and for current debates in the philosophy of modality, a phenomenologist may want to ask whether it makes sense to speak of “possible worlds” in phenomenology. The answer will depend on how "possible worlds" are to be interpreted. As that latter question is the subject of the debate about possibilism and actualism in contemporary modal metaphysics, my aim in this paper is to get a better grip on the former question by exploring a Husserlian stance towards this debate. I will argue that the phenomenologist’s way to deal with the problem of intentional reference to mere possibilia is analogous to the actualist’s idea of how “possible worlds” are to be interpreted. Nevertheless, I will be pointing to a decisive difference in the metaphilosophical preconditions of what I call "phenomenological actualism" and analytical versions of actualism

    Light-Quark Resonances at COMPASS

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    The main goal of the spectroscopy program at COMPASS is to explore the light-meson spectrum in the mass range below about 2GeV/c22\,\text{GeV}/c^2 using diffractive dissociation reactions. Our flagship channel is the production of three charged pions in the reaction: π+pπππ++precoil\pi^- + p \to \pi^-\pi^-\pi^+ + p_\text{recoil}, for which COMPASS has acquired the so far world's largest dataset of roughly 50M50\,\text{M} exclusive events using an 190GeV/c190\,\text{GeV}/c π\pi^- beam. In order to extract the parameters of the πJ\pi_J and aJa_J resonances that appear in the πππ+\pi^-\pi^-\pi^+ system, we performed the so far most comprehensive resonance-model fit, using Breit-Wigner parametrizations. This method in combination with the high statistical precision of our data allows us to study ground and excited states. We study the a4(2040)a_4(2040) resonance in the ρ(770)πG\rho(770)\pi G and f2(1270)πFf_2(1270)\pi F decays. In addition to the ground state resonance a1(1260)a_1(1260), we have found evidence for the a1(1640)a_1(1640). We also study the spectrum of π2\pi_2 states by simultaneously describing four JPC=2+J^{PC}=2^{-+} waves using three π2\pi_2 resonances, the π2(1670)\pi_2(1670), the π2(1880)\pi_2(1880), and the π2(2005)\pi_2(2005). Using a novel analysis approach, where the resonance-model fit is performed simultaneously in narrow bins of the squared four-momentum transfer tt' between the beam pion and the target proton, allows us to study the tt' dependence of resonant and non-resonant components included in our model. We observe that for most of the partial waves, the non-resonant components show a steeper tt' spectrum compared to the resonances and that the tt' spectrum of most of the resonances becomes shallower with increasing resonance mass. We also study the tt' dependence of the relative phases between resonance components. The pattern we observe is consistent with a common production mechanism of these states

    The ground of ground, essence, and explanation

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    This paper is about the so-called meta-grounding question, i.e. the question of what grounds grounding facts of the sort ‘φ is grounded in Γ ’. An answer to this question is pressing since some plausible assumptions about grounding and fundamentality entail that grounding facts must be grounded. There are three different accounts on the market which each answer the meta-grounding question differently: Bennett’s and deRosset’s “Straight Forward Account” (SFA), Litland’s “Zero-Grounding Account” (ZGA), and “Grounding Essentialism” (GE). I argue that if grounding is to be regarded as metaphysical explanation (i.e. if unionism is true), (GE) is to be preferred over (ZGA) and (SFA) as only (GE) is compatible with a crucial consequence of the thought that grounding is metaphysical explanation. In this manner the paper contributes not only to discussions about the ground of ground but also to the ongoing debate concerning the relationship between ground, essence, and explanation

    Tree Parity Machine Rekeying Architectures

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    The necessity to secure the communication between hardware components in embedded systems becomes increasingly important with regard to the secrecy of data and particularly its commercial use. We suggest a low-cost (i.e. small logic-area) solution for flexible security levels and short key lifetimes. The basis is an approach for symmetric key exchange using the synchronisation of Tree Parity Machines. Fast successive key generation enables a key exchange within a few milliseconds, given realistic communication channels with a limited bandwidth. For demonstration we evaluate characteristics of a standard-cell ASIC design realisation as IP-core in 0.18-micrometer CMOS-technology

    Lattice paths of slope 2/5

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    We analyze some enumerative and asymptotic properties of Dyck paths under a line of slope 2/5.This answers to Knuth's problem \\#4 from his "Flajolet lecture" during the conference "Analysis of Algorithms" (AofA'2014) in Paris in June 2014.Our approach relies on the work of Banderier and Flajolet for asymptotics and enumeration of directed lattice paths. A key ingredient in the proof is the generalization of an old trick of Knuth himself (for enumerating permutations sortable by a stack),promoted by Flajolet and others as the "kernel method". All the corresponding generating functions are algebraic,and they offer some new combinatorial identities, which can be also tackled in the A=B spirit of Wilf--Zeilberger--Petkov{\v s}ek.We show how to obtain similar results for other slopes than 2/5, an interesting case being e.g. Dyck paths below the slope 2/3, which corresponds to the so called Duchon's club model.Comment: Robert Sedgewick and Mark Daniel Ward. Analytic Algorithmics and Combinatorics (ANALCO)2015, Jan 2015, San Diego, United States. SIAM, 2015 Proceedings of the Twelfth Workshop on Analytic Algorithmics and Combinatorics (ANALCO), eISBN 978-1-61197-376-1, pp.105-113, 2015, 2015 Proceedings of the Twelfth Workshop on Analytic Algorithmics and Combinatorics (ANALCO