The halting problem and security’s language-theoretic approach: Praise and criticism from a technical historian

Computability ◽  
2020 ◽  
pp. 1-18
Author(s):  
Edgar G. Daylight
Keyword(s):  
Computability Theory ◽  
Impossibility Result ◽  
Theoretic Approach ◽  
Halting Problem ◽  
Mathematical Objects ◽  
The Core ◽  
Conceptual Clarity ◽  
Computer Professionals

The term ‘Halting Problem’ arguably refers to computer science’s most celebrated impossibility result and to the core notion underlying the language-theoretic approach to security. Computer professionals often ignore the Halting Problem however. In retrospect, this is not too surprising given that several advocates of computability theory implicitly follow Christopher Strachey’s alleged 1965 proof of his Halting Problem (which is about executable – i.e., hackable – programs) rather than Martin Davis’s correct 1958 version or his 1994 account (each of which is solely about mathematical objects). For the sake of conceptual clarity, particularly for researchers pursuing a coherent science of cybersecurity, I will scrutinize Strachey’s 1965 line of reasoning – which is widespread today – both from a charitable, historical angle and from a critical, engineering perspective.

scholarly journals Living models or life modelled? On the use of models in the free energy principle

2020 ◽  
pp. 105971232091867
Author(s):  
Thomas van Es
Keyword(s):  
Free Energy ◽  
Second Law Of Thermodynamics ◽  
Living Systems ◽  
Theoretic Approach ◽  
Energy Principle ◽  
Free Energy Principle ◽  
Information Theoretic ◽  
Conceptual Clarity ◽  
The Status ◽  
Information Theoretic Approach

The free energy principle (FEP) is an information-theoretic approach to living systems. FEP characterizes life by living systems’ resistance to the second law of thermodynamics: living systems do not randomly visit the possible states, but actively work to remain within a set of viable states. In FEP, this is modelled mathematically. Yet, the status of these models is typically unclear: are these models employed by organisms or strictly scientific tools of understanding? In this article, I argue for an instrumentalist take on models in FEP. I shall argue that models used as instruments for knowledge by scientists and models as implemented by organisms to navigate the world are being conflated, which leads to erroneous conclusions. I further argue that a realist position is unwarranted. First, it overgenerates models and thus trivializes the notion of modelling. Second, even when the mathematical mechanisms described by FEP are implemented in an organism, they do not constitute a model. They are covariational, not representational in nature, and precede the social practices that have shaped our scientific modelling practice. I finally argue that the above arguments do not affect the instrumentalist position. An instrumentalist approach can further add to conceptual clarity in the FEP literature.

Hydropolitics

2020 ◽  
Author(s):  
Mattia Grandi
Keyword(s):  
International Relations ◽  
State Level ◽  
Critical Geopolitics ◽  
Disciplinary Boundaries ◽  
The Core ◽  
Theoretical Perspectives ◽  
Conceptual Clarity ◽  
Knowledge Theory ◽  
International Water ◽  
Core Features

The lack of a settled definition for hydropolitics—a prismatic concept that acquires specific meanings according to both the disciplinary boundaries within which it is used and the theoretical perspectives of those employing it—is consistent with the disagreement over its nomenclature (hydro-politics vs. hydropolitics). The term has had many meanings and idiosyncratic usages over time, and there has been hardly any attempt to advance a clear definition for it. The strength of the concept of hydropolitics, its inter-disciplinary conceptual heterogeneity, is also its weakness. While the crystallization of some of the core features of hydropolitics in the literature—especially with regard to scale (namely, the focus on the inter-state level and the range of issues covered, that is, the politics of international water basins)—has anchored hydropolitics to “standard cases” of the concept, its theoretical underpinnings are still blurred. The study of hydropolitics has substantially delved into trans-boundary, not just any, waters. Yet, both the ontology and epistemology of the concept are debatable, so few eclectic definitions for hydropolitics have emerged. Hence, by addressing the relationships between knowledge, theory, and action of hydropolitics, the scientific community, in particular scholars of international relations, political geography, and critical geopolitics, has struggled for theoretical coherence as well as for conceptual clarity over the use of the term. This is not an easy task, though, because the fluid essence of hydropolitics escapes not only definition but also easy classification.

scholarly journals Allocation of Environmental Impacts in Circular and Cascade Use of Resources—Incentive-Driven Allocation as a Prerequisite for Cascade Persistence

2020 ◽  
Vol 12 (11) ◽  
pp. 4366
Author(s):  
Max Rehberger ◽  
Michael Hiete
Keyword(s):  
Environmental Impacts ◽  
Shapley Value ◽  
Theoretic Approach ◽  
The Core ◽  
Use Of Resources ◽  
The Shapley Value ◽  
Game Theoretic ◽  
Set Up ◽  
Generic Set

In cascade use, a resource is used consecutively in different application areas demanding less and less quality. As this practically allows using the same resource several times, cascading contributes to resource efficiency and a circular economy and, therefore, has gained interest recently. To assess the advantages of cascading and to distribute the environmental impacts arising from resource extraction/processing, potentially needed treatment and upcycling within the cascade chain and end-of-life proesses represent a difficult task within life cycle assessment and highlight the needs for a widely applicable and acceptable framework of how to allocate the impacts. To get insight into how the allocation is handled in cascades, a systematic literature review was carried out. Starting from this status quo, common allocation approaches were extracted, harmonized, and evaluated for which a generic set of criteria was deduced from the literature. Most importantly, participants must be willing to set up a cascade, which requires that for each participant, there are individual benefits, e.g., getting less environmental burdens allocated than if not joining. A game-theoretic approach based on the concept of the core and the Shapley value was presented, and the approaches were benchmarked against this in a case-study setting. Several of the approaches laid outside the core, i.e., they did not give an incentive to the participants to join the cascade in the case study. Their application for cascade use is, therefore, debatable. The core was identified as an approach for identifying suitable allocation procedures for a problem at hand, and the Shapley value identified as a slightly more complex but fair allocation procedure.

Avicenna against Mathematical Platonism

Oriens ◽  
2019 ◽  
Vol 47 (3-4) ◽  
pp. 197-243
Author(s):  
Mohammad Saleh Zarepour
Keyword(s):  
Philosophy Of Mathematics ◽  
Mathematical Objects ◽  
The Core ◽  
Mathematical Platonism

Abstract In this paper I investigate Avicenna’s criticisms of the separateness of mathematical objects and of the view that they are principles for natural things. These two theses form the core of Plato’s view of mathematics; i.e., mathematical Platonism. Surprisingly, Avicenna does not consider his arguments against these theses as attacks on Plato. This is because his understanding of Plato’s philosophy of mathematics differs from both Plato’s original view and what Aristotle attributes to Plato.

Variable morphotactics in Information-based Morphology

2015 ◽  
Vol 52 (2) ◽  
pp. 311-374 ◽  
Author(s):  
BERTHOLD CRYSMANN ◽  
OLIVIER BONAMI
Keyword(s):  
Formal Theory ◽  
Inflectional Morphology ◽  
Theoretic Approach ◽  
The Core ◽  
Rule Type ◽  
Feature Structures ◽  
Different Types ◽  
Nominal Declension ◽  
Extended Discussion ◽  
Order Variability

We address variable morphotactics, the phenomenon of order variability of morphs, in the context of inflectional morphology. Based on an extended discussion of cross-linguistic variation, including conjugation in Nepali, Fula, Swahili, Chintang and Italian, and nominal declension in Ostyak and Mari, we propose a canonical typology that identifies different deviations from strict ordering. Following a discussion of previous approaches to the problem, we propose Information-based Morphology, an inferential-realisational and model-theoretic approach to morphology couched in a logic of typed feature structures. Within this formal theory, we develop detailed analyses of the core cases in the typology and show how different types and degrees of deviation from the canon can be pin-pointed in the relative complexity of the rule type hierarchies that model the data. Furthermore, we show that complex deviations, as attested in Mari, can be understood as combinations of more basic deviations.

scholarly journals A generic systems-theoretic approach to identify biological networks capable of adaptation

2021 ◽  
Author(s):  
Priyan Bhattacharya ◽  
Karthik Raman ◽  
Arun Kumar Tangirala
Keyword(s):  
Systems Theory ◽  
Biological Networks ◽  
Living Organism ◽  
Design Principles ◽  
Theoretic Approach ◽  
Third Order ◽  
The Core ◽  
Node Network ◽  
Design Requirements ◽  
Theoretical Results

Constructing biological networks capable of performing specific biological functionalities has been of sustained interest in synthetic biology. Adaptation is one such ubiquitous functional property, which enables every living organism to sense a change in its surroundings and return to its operating condition prior to the disturbance. In this paper, we present a generic systems theory-driven method for designing adaptive protein networks. First, we translate the necessary qualitative conditions for adaptation to mathematical constraints using the language of systems theory, which we then map back as 'design requirements' for the underlying networks. We go on to prove that a protein network with different input--output nodes (proteins) needs to be at least of third-order in order to provide adaptation. Next, we show that the necessary design principles obtained for a three-node network in adaptation consist of negative feedback or a feed-forward realization. Interestingly, the design principles obtained by the proposed method remain the same for a network of arbitrary size and connectivity. Finally, we prove that the motifs discovered for adaptation are non-retroactive for a canonical downstream connection. This result explains how complex biological networks achieve robustness while keeping the core motifs unchanged in the context of a particular functionality. We corroborate our theoretical results with detailed and thorough numerical simulations. Overall, our results present a generic, systematic and robust framework for designing various kinds of biological networks.

What face familiarity feelings say about the lateralization of specific entities within the core system

2019 ◽  
Vol 42 ◽  
Author(s):  
Guido Gainotti
Keyword(s):  
Temporal Lobe ◽  
Memory System ◽  
Core System ◽  
The Core ◽  
Memory Traces ◽  
Specific Memory ◽  
Target Article ◽  
Temporal Structures ◽  
The Right

Abstract The target article carefully describes the memory system, centered on the temporal lobe that builds specific memory traces. It does not, however, mention the laterality effects that exist within this system. This commentary briefly surveys evidence showing that clear asymmetries exist within the temporal lobe structures subserving the core system and that the right temporal structures mainly underpin face familiarity feelings.

A scanning electron microscopic study on dissolving process of cholesterol gallstones by chenodeoxycholic acid (CDCA)

1978 ◽  
Vol 36 (2) ◽  
pp. 522-523
Author(s):  
T. Kanetaka ◽  
M. Cho ◽  
S. Kawamura ◽  
T. Sado ◽  
K. Hara
Keyword(s):  
Electron Microscope ◽  
Chenodeoxycholic Acid ◽  
Outer Surface ◽  
Electron Microscopic ◽  
Cholesterol Gallstones ◽  
The Core ◽  
Scanning Electron Microscopic Study ◽  
Scanning Electron Microscopic ◽  
Acceleration Voltage ◽  
Scanning Electron

The authors have investigated the dissolution process of human cholesterol gallstones using a scanning electron microscope(SEM). This study was carried out by comparing control gallstones incubated in beagle bile with gallstones obtained from patients who were treated with chenodeoxycholic acid(CDCA).The cholesterol gallstones for this study were obtained from 14 patients. Three control patients were treated without CDCA and eleven patients were treated with CDCA 300-600 mg/day for periods ranging from four to twenty five months. It was confirmed through chemical analysis that these gallstones contained more than 80% cholesterol in both the outer surface and the core.The specimen were obtained from the outer surface and the core of the gallstones. Each specimen was attached to alminum sheet and coated with carbon to 100Å thickness. The SEM observation was made by Hitachi S-550 with 20 kV acceleration voltage and with 60-20, 000X magnification.

The Structure and Development of Microbodies in the Fat Body and other Tissues of an Insect (Calpodes Ethlius)

1970 ◽  
Vol 28 ◽  
pp. 148-149
Author(s):  
M. Locke ◽  
J. T. McMahon
Keyword(s):  
Electron Microscopy ◽  
Liquid Crystals ◽  
Fat Body ◽  
Competitive Inhibitor ◽  
Dense Core ◽  
Urate Oxidase ◽  
Blood Proteins ◽  
Free Base ◽  
The Core ◽  
The Matrix

The fat body of insects has always been compared functionally to the liver of vertebrates. Both synthesize and store glycogen and lipid and are concerned with the formation of blood proteins. The comparison becomes even more apt with the discovery of microbodies and the localization of urate oxidase and catalase in insect fat body.The microbodies are oval to spherical bodies about 1μ across with a depression and dense core on one side. The core is made of coiled tubules together with dense material close to the depressed membrane. The tubules may appear loose or densely packed but always intertwined like liquid crystals, never straight as in solid crystals (Fig. 1). When fat body is reacted with diaminobenzidine free base and H2O2 at pH 9.0 to determine the distribution of catalase, electron microscopy shows the enzyme in the matrix of the microbodies (Fig. 2). The reaction is abolished by 3-amino-1, 2, 4-triazole, a competitive inhibitor of catalase. The fat body is the only tissue which consistantly reacts positively for urate oxidase. The reaction product is sharply localized in granules of about the same size and distribution as the microbodies. The reaction is inhibited by 2, 6, 8-trichloropurine, a competitive inhibitor of urate oxidase.

Exsolution and inversion in pigeonite from the Whin Sill, Northern England

1978 ◽  
Vol 36 (1) ◽  
pp. 474-475
Author(s):  
P.P.K. Smith
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Homogeneous Nucleation ◽  
Silicate Mineral ◽  
Antiphase Boundaries ◽  
Two Phase ◽  
Primitive Form ◽  
The Core ◽  
Nucleation Mechanisms ◽  
And Inversion

Grains of pigeonite, a calcium-poor silicate mineral of the pyroxene group, from the Whin Sill dolerite have been ion-thinned and examined by TEM. The pigeonite is strongly zoned chemically from the composition Wo8En64FS28 in the core to Wo13En34FS53 at the rim. Two phase transformations have occurred during the cooling of this pigeonite:- exsolution of augite, a more calcic pyroxene, and inversion of the pigeonite from the high- temperature C face-centred form to the low-temperature primitive form, with the formation of antiphase boundaries (APB's). Different sequences of these exsolution and inversion reactions, together with different nucleation mechanisms of the augite, have created three distinct microstructures depending on the position in the grain.In the core of the grains small platelets of augite about 0.02μm thick have farmed parallel to the (001) plane (Fig. 1). These are thought to have exsolved by homogeneous nucleation. Subsequently the inversion of the pigeonite has led to the creation of APB's.

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