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Articles 141601 - 141630 of 303004

Full-Text Articles in Physical Sciences and Mathematics

Full Issue, Volume Iii Jun 2015

Full Issue, Volume Iii

The Catch

No abstract provided.

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Dependent Types And Program Equivalence, Limin Jia, Jianzhou Zhao, Vilhelm Sjoberg, Stephanie Weirich Jun 2015

Dependent Types And Program Equivalence, Limin Jia, Jianzhou Zhao, Vilhelm Sjoberg, Stephanie Weirich

Stephanie Weirich

The definition of type equivalence is one of the most important design issues for any typed language. In dependently-typed languages, because terms appear in types, this definition must rely on a definition of term equivalence. In that case, decidability of type checking requires decidability for the term equivalence relation. Almost all dependently-typed languages require this relation to be decidable. Some, such as Coq, Epigram or Agda, do so by employing analyses to force all programs to terminate. Conversely, others, such as DML, ATS, Omega, or Haskell, allow nonterminating computation, but do not allow those terms to appear in types. Instead, …

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Generative Type Abstraction And Type-Level Computation, Stephanie Weirich, Dimitrios Vytiniotis, Simon Peyton Jones, Stephan A. Zdancewic Jun 2015

Generative Type Abstraction And Type-Level Computation, Stephanie Weirich, Dimitrios Vytiniotis, Simon Peyton Jones, Stephan A. Zdancewic

Stephanie Weirich

Modular languages support generative type abstraction, ensuring that an abstract type is distinct from its representation, except inside the implementation where the two are synonymous. We show that this well-established feature is in tension with the non-parametric features of newer type systems, such as indexed type families and GADTs. In this paper we solve the problem by using kinds to distinguish between parametric and non-parametric contexts. The result is directly applicable to Haskell, which is rapidly developing support for type-level computation, but the same issues should arise whenever generativity and non-parametric features are combined.

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Towards Synthesis Of Platform-Aware Attack-Resilient Control Systems: Extended Abstract, Miroslav Pajic, Nicola Bezzo, James Weimer, Rajeev Alur, Rahul Mangharam, Nathan Michael, George Pappas, Oleg Sokolsky, Paulo Tabuada, Stephanie Weirich, Insup Lee Jun 2015

Towards Synthesis Of Platform-Aware Attack-Resilient Control Systems: Extended Abstract, Miroslav Pajic, Nicola Bezzo, James Weimer, Rajeev Alur, Rahul Mangharam, Nathan Michael, George Pappas, Oleg Sokolsky, Paulo Tabuada, Stephanie Weirich, Insup Lee

Stephanie Weirich

No abstract provided.

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Reactive Noninterference, Aaron Bohannon, Benjamin C. Pierce, Vilhelm Sjoberg, Stephanie Weirich, Stephan A. Zdancewic Jun 2015

Reactive Noninterference, Aaron Bohannon, Benjamin C. Pierce, Vilhelm Sjoberg, Stephanie Weirich, Stephan A. Zdancewic

Stephanie Weirich

Many programs operate reactively-patiently waiting for user input, running for a while producing output, and eventually returning to a state where they are ready to accept another input (or occasionally diverging). When a reactive program communicates with multiple parties, we would like to be sure that it can be given secret information by one without leaking it to others. Motivated by web browsers and client-side web applications, we explore definitions of noninterference for reactive programs and identify two of special interest-one corresponding to termination-insensitive noninterference for a simple sequential language, the other to termination-sensitive noninterference. We focus on the former …

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Step-Indexed Normalization For A Language With General Recursion, Chris Cainghino, Vilhelm Sjoberg, Stephanie Weirich Jun 2015

Step-Indexed Normalization For A Language With General Recursion, Chris Cainghino, Vilhelm Sjoberg, Stephanie Weirich

Stephanie Weirich

The TRELLYS project has produced several designs for practical dependently typed languages. These languages are broken into two fragments—a logical fragment where every term normalizes and which is consistent when interpreted as a logic, and a programmatic fragment with general recursion and other convenient but unsound features. In this paper, we present a small example language in this style. Our design allows the programmer to explicitly mention and pass information between the two fragments. We show that this feature substantially complicates the metatheory and present a new technique, combining the traditional Girard–Tait method with step-indexed logical relations, which we use …

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Irrelevance, Heterogeneous Equity, And Call-By-Value Dependent Type Systems, Vilhelm Sjoberg, Chris Casinghino, Nathan Collins, Ki Yung Ahn, Tim Sheard, Harley D. Eades Iii, Peng Fu, Garrin Kimmell, Aaron Stump, Stephanie Weirich Jun 2015

Irrelevance, Heterogeneous Equity, And Call-By-Value Dependent Type Systems, Vilhelm Sjoberg, Chris Casinghino, Nathan Collins, Ki Yung Ahn, Tim Sheard, Harley D. Eades Iii, Peng Fu, Garrin Kimmell, Aaron Stump, Stephanie Weirich

Stephanie Weirich

We present a full-spectrum dependently typed core language which includes both nontermination and computational irrelevance (a.k.a. erasure), a combination which has not been studied before. The two features interact: to protect type safety we must be careful to only erase terminating expressions. Our language design is strongly influenced by the choice of CBV evaluation, and by our novel treatment of propositional equality which has a heterogeneous, completely erased elimination form.

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Contracts Made Manifest, Michael Greenberg, Benjamin C. Pierce, Stephanie Weirich Jun 2015

Contracts Made Manifest, Michael Greenberg, Benjamin C. Pierce, Stephanie Weirich

Stephanie Weirich

Since Findler and Felleisen (Findler, R. B. & Felleisen, M. 2002) introduced higher-order contracts, many variants have been proposed. Broadly, these fall into two groups: some follow Findler and Felleisen (2002) in using latent contracts, purely dynamic checks that are transparent to the type system; others use manifest contracts, where refinement types record the most recent check that has been applied to each value. These two approaches are commonly assumed to be equivalent—different ways of implementing the same idea, one retaining a simple type system, and the other providing more static information. Our goal is to formalize and clarify this …

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Giving Haskell A Promotion, Stephanie Weirich, Brent A. Yorgey, Julien Cretin, Simon Peyton Jones, Dimitrios Vytiniotis, Jose P. Magalhaes Jun 2015

Giving Haskell A Promotion, Stephanie Weirich, Brent A. Yorgey, Julien Cretin, Simon Peyton Jones, Dimitrios Vytiniotis, Jose P. Magalhaes

Stephanie Weirich

Static type systems strive to be richly expressive while still being simple enough for programmers to use. We describe an experiment that enriches Haskell’s kind system with two features promoted from its type system: data types and polymorphism. The new system has a very good power-to-weight ratio: it offers a significant improvement in expressiveness, but, by re-using concepts that programmers are already familiar with, the system is easy to understand and implement.

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Arity-Generic Datatype-Generic Programming, Stephanie Weirich, Chris Casinghino Jun 2015

Arity-Generic Datatype-Generic Programming, Stephanie Weirich, Chris Casinghino

Stephanie Weirich

Some programs are doubly-generic. For example, map is datatypegeneric in that many different data structures support a mapping operation. A generic programming language like Generic Haskell can use a single definition to generate map for each type. However, map is also arity-generic because it belongs to a family of related operations that differ in the number of arguments. For lists, this family includes repeat, map, zipWith, zipWith3, zipWith4, etc. With dependent types or clever programming, one can unify all of these functions together in a single definition. However, no one has explored the combination of these two forms of genericity. …

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Language-Based Verification Will Change The World, Tim Sheard, Aaron Stump, Stephanie Weirich Jun 2015

Language-Based Verification Will Change The World, Tim Sheard, Aaron Stump, Stephanie Weirich

Stephanie Weirich

We argue that lightweight, language-based verification is poised to enter mainstream industrial use, where it will have a major impact on software quality and reliability. We explain how language-based approaches based on so-called dependent types are already being adopted in functional programming languages, and why such methods will be successful for mainstream use, where traditional formal methods have failed.

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Combining Proofs And Programs In A Dependently Typed Language, Stephanie Weirich, Vilhelm Sjoberg, Chris Casinghino Jun 2015

Combining Proofs And Programs In A Dependently Typed Language, Stephanie Weirich, Vilhelm Sjoberg, Chris Casinghino

Stephanie Weirich

Most dependently-typed programming languages either require that all expressions terminate (e.g. Coq, Agda, and Epigram), or allow infinite loops but are inconsistent when viewed as logics (e.g. Haskell, ATS, mega). Here, we combine these two approaches into a single dependently-typed core language. The language is composed of two fragments that share a common syntax and overlapping semantics: a logic that guarantees total correctness, and a call-by-value programming language that guarantees type safety but not termination. The two fragments may interact: logical expressions may be used as programs; the logic may soundly reason about potentially nonterminating programs; programs can require logical …

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Parametricity, Type Equality And Higher-Order Polymorphism, Dimitrios Vytiniotis, Stephanie Weirich Jun 2015

Parametricity, Type Equality And Higher-Order Polymorphism, Dimitrios Vytiniotis, Stephanie Weirich

Stephanie Weirich

Propositions that express type equality are a frequent ingredient of modern functional programming|they can encode generic functions, dynamic types, and GADTs. Via the Curry-Howard correspondence, these propositions are ordinary types inhabited by proof terms, computed using runtime type representations. In this paper we show that two examples of type equality propositions actually do re ect type equality; they are only inhabited when their arguments are equal and their proofs are unique (up to equivalence.) We show this result in the context of a strongly normalizing language with higher-order polymorphism and primitive recursion over runtime type representations by proving Reynolds's abstraction …

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Programming Up To Congruence (Extended Version), Vilhelm Sjoberg, Stephanie Weirich Jun 2015

Programming Up To Congruence (Extended Version), Vilhelm Sjoberg, Stephanie Weirich

Stephanie Weirich

This paper presents the design of ZOMBIE, a dependently-typed programming language that uses an adaptation of a congruence closure algorithm for proof and type inference. This algorithm allows the type checker to automatically use equality assumptions from the context when reasoning about equality. Most dependently typed languages automatically use equalities that follow from -reduction during type checking; however, such reasoning is incompatible with congruence closure. In contrast, ZOMBIE does not use automatic -reduction because types may contain potentially diverging terms. Therefore ZOMBIE provides a unique opportunity to explore an alternative definition of equivalence in dependently typed language design. Our work …

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Equational Reasoning About Programs With General Recursion And Call-By-Value Semantics, Garrin Kimmell, Aaron Stump, Harley D. Eades Iii, Peng Fu, Tim Sheard, Stephanie Weirich, Chris Casinghino, Vilhelm Sjoberg, Nathan Collins, Ki Yung Ahn Jun 2015

Equational Reasoning About Programs With General Recursion And Call-By-Value Semantics, Garrin Kimmell, Aaron Stump, Harley D. Eades Iii, Peng Fu, Tim Sheard, Stephanie Weirich, Chris Casinghino, Vilhelm Sjoberg, Nathan Collins, Ki Yung Ahn

Stephanie Weirich

Dependently typed programming languages provide a mechanism for integrating verification and programming by encoding invariants as types. Traditionally, dependently typed languages have been based on constructive type theories, where the connection between proofs and programs is based on the Curry-Howard correspondence. This connection comes at a price, however, as it is necessary for the languages to be normalizing to preserve logical soundness. Trellys is a call-by-value dependently typed programming language currently in development that is designed to integrate a type theory with unsound programming features, such as general recursion, Type:Type, and others. In this paper we outline one core language …

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Closed Type Families With Overlapping Equations (Extended Version), Richard A. Eisenberg, Dimitrios Vytiniotis, Simon Peyton Jones, Stephanie Weirich Jun 2015

Closed Type Families With Overlapping Equations (Extended Version), Richard A. Eisenberg, Dimitrios Vytiniotis, Simon Peyton Jones, Stephanie Weirich

Stephanie Weirich

Open, type-level functions are a recent innovation in Haskell that move Haskell towards the expressiveness of dependent types, while retaining the look and feel of a practical programming language. This paper shows how to increase expressiveness still further, by adding closed type functions whose equations may overlap, and may have non-linear patterns over an open type universe. Although practically useful and simple to implement, these features go beyond conventional dependent type theory in some respects, and have a subtle metatheory.

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Would Student Learning Orientation Impact Upon Preference Of Communication Media Usage?, Hongjiang Xu, Priscilla Arling Jun 2015

Would Student Learning Orientation Impact Upon Preference Of Communication Media Usage?, Hongjiang Xu, Priscilla Arling

Priscilla Arling

Different students have different learning orientations. Some of them focus on learning, some of the focus on grade, and some focus on both. Students’ learning orientations have been studies with students’ attitudes towards educations, and their experience with higher educations. In this study, we would like to investigate in higher education, whether students’ learning orientations have impact upon students’ preference of communication media usage. Understanding students’ media usage preference would help to establish the best way to communicate with different type of students. This is particular useful for identifying the strategy for hybrid/ online learning for different type of students.

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U.S. Drought Monitor, June 2, 2015, David Miskus Jun 2015

U.S. Drought Monitor, June 2, 2015, David Miskus

United States Agricultural Commodities in Drought Archive

Drought map of U.S. for June 2, 2015 (6/2/15) plus: U.S. crop areas experiencing drought (map), Approximate percentage of crop located in drought, by state (bar graph), Percent of crop area located in drought, past 52 weeks (line graph) for: Corn, Soybeans, Hay, Cattle, Winter wheat.

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Developing A Physics Expert Identity In A Biophysics Research Group, Idaykis Rodriguez, Michelle Goertzen, Eric Brewe, Laird H. Kramer Jun 2015

Developing A Physics Expert Identity In A Biophysics Research Group, Idaykis Rodriguez, Michelle Goertzen, Eric Brewe, Laird H. Kramer

Stem Transformation Institute

We investigate the development of expert identities through the use of the sociocultural perspective of learning as participating in a community of practice. An ethnographic case study of biophysics graduate students focuses on the experiences the students have in their research group meetings. The analysis illustrates how the communities of practice-based identity constructs of competencies characterize student expert membership. A microanalysis of speech, sound, tones, and gestures in video data characterize students’ social competencies in the physics community of practice. Results provide evidence that students at different stages of their individual projects have opportunities to develop social competencies such as …

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Three Super-Earths Orbiting Hd 7924, Benjamin J. Fulton, Lauren M. Weiss, Evan Sinukoff, Howard Isaacson, Andrew W. Howard, Geoffrey W. Marcy, Gregory W. Henry, Bradford P. Holden, Robert I. Kibrick Jun 2015

Three Super-Earths Orbiting Hd 7924, Benjamin J. Fulton, Lauren M. Weiss, Evan Sinukoff, Howard Isaacson, Andrew W. Howard, Geoffrey W. Marcy, Gregory W. Henry, Bradford P. Holden, Robert I. Kibrick

Information Systems and Engineering Management Research Publications

We report the discovery of two super-Earth-mass planets orbiting the nearby K0.5 dwarf HD 7924, which was previously known to host one small planet. The new companions have masses of 7.9 and 6.4 ${{M}_{\oplus }}$, and orbital periods of 15.3 and 24.5 days. We perform a joint analysis of high-precision radial velocity data from Keck/HIRES and the new Automated Planet Finder Telescope (APF) to robustly detect three total planets in the system. We refine the ephemeris of the previously known planet using 5 yr of new Keck data and high-cadence observations over the last 1.3 yr with the APF. With …

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Wallis On Indivisibles, Antoni Malet, Marco Panza Jun 2015

Wallis On Indivisibles, Antoni Malet, Marco Panza

MPP Published Research

The present chapter is devoted, first, to discuss in detail the structure and results of Wallis’s major and most influential mathematical work, the Arithmetica Infinitorum (Wallis 1656). Next we will revise Wallis’s views on indivisibles as articulated in his answer to Hobbes’s criticism in the early 1670s. Finally, we will turn to his discussion of the proper way to understand the angle of contingence in the first half of the 1680s. As we shall see, there are marked differences in the status that indivisibles seem to enjoy in Wallis’s thought along his mathematical career. These differences correlate with the changing …

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Newton On Indivisibles, Antoni Malet, Marco Panza Jun 2015

Newton On Indivisibles, Antoni Malet, Marco Panza

MPP Published Research

Though Wallis’s Arithmetica infinitorum was one of Newton’s major sources of inspiration during the first years of his mathematical education, indivisibles were not a central feature of his mathematical production.

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Technical Communication As Teaching: A Grounded Theory Study Of Cognitive Empathy And Audience Engagement Among Computer Science Majors In A Technical Communication Classroom, Robert Michael Rowan Jun 2015

Technical Communication As Teaching: A Grounded Theory Study Of Cognitive Empathy And Audience Engagement Among Computer Science Majors In A Technical Communication Classroom, Robert Michael Rowan

Theses and Dissertations

This dissertation is a grounded theory study of empathy, ethical awareness, and audience engagement activities in students in a technical writing service course. The course was designed around an empathy-oriented approach to teaching technical writing and writing research. The students are primarily computer science majors, and the teaching methods include a genre and writing research approach as well as the use of an extended metaphor of technical communication as a form of teaching. Findings indicate that students respond to the metaphor by drawing upon positive and empathetically-informed models of teachers and teaching to guide how they would work with and …

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An Investigation Of The Role Of Alternate Numeration Systems In Preservice Teacher Mathematics Content Courses, Jodi I. Fasteen Jun 2015

An Investigation Of The Role Of Alternate Numeration Systems In Preservice Teacher Mathematics Content Courses, Jodi I. Fasteen

Dissertations and Theses

Alternate numeration systems are common in preservice teacher (PST) mathematics curricula, but there is limited research on how to leverage alternate systems to promote the development of mathematical knowledge for teaching. I analyzed the role of alternate numeration systems in three ways. I conducted a thematic analysis of current PST textbooks to consider the role of alternate numeration systems in written curricula. I conducted a teaching experiment to analyze PSTs' mathematical activity as they engaged with a base five task sequence to reinvent an algorithm for multiplication. And I introduced problematizing mathematical contexts as a design heuristic, situating this within …

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Gps Phase Scintillation At High Latitudes During Geomagnetic Storms Of 7–17 March 2012 – Part 1: The North American Sector, P. Prikryl, R. Ghoddousi-Fard, E. G. Thomas, J. M. Ruohoniemi, S. G. Shepherd Jun 2015

Gps Phase Scintillation At High Latitudes During Geomagnetic Storms Of 7–17 March 2012 – Part 1: The North American Sector, P. Prikryl, R. Ghoddousi-Fard, E. G. Thomas, J. M. Ruohoniemi, S. G. Shepherd

Dartmouth Scholarship

During the ascending phase of solar cycle 24, a series of interplanetary coronal mass ejections (ICMEs) in the period 7–17 March 2012 caused geomagnetic storms that strongly affected high-latitude ionosphere in the Northern and Southern Hemisphere. GPS phase scintillation was observed at northern and southern high latitudes by arrays of GPS ionospheric scintillation and TEC monitors (GISTMs) and geodetic-quality GPS receivers sampling at 1 Hz. Mapped as a function of magnetic latitude and magnetic local time, regions of enhanced scintillation are identified in the context of coupling processes between the solar wind and the magnetosphere–ionosphere system. Large southward IMF and …

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Hardware/Software Interface Assurance With Conformance Checking, Li Lei Jun 2015

Hardware/Software Interface Assurance With Conformance Checking, Li Lei

Dissertations and Theses

Hardware/Software (HW/SW) interfaces are pervasive in modern computer systems. Most of HW/SW interfaces are implemented by devices and their device drivers. Unfortunately, HW/SW interfaces are unreliable and insecure due to their intrinsic complexity and error-prone nature. Moreover, assuring HW/SW interface reliability and security is challenging. First, at the post-silicon validation stage, HW/SW integration validation is largely an ad-hoc and time-consuming process. Second, at the system deployment stage, transient hardware failures and malicious attacks make HW/SW interfaces vulnerable even after intensive testing and validation. In this dissertation, we present a comprehensive solution for HW/SW interface assurance over the system life cycle. …

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Novel Methods For Learning And Adaptation In Chemical Reaction Networks, Peter Banda Jun 2015

Novel Methods For Learning And Adaptation In Chemical Reaction Networks, Peter Banda

Dissertations and Theses

State-of-the-art biochemical systems for medical applications and chemical computing are application-specific and cannot be re-programmed or trained once fabricated. The implementation of adaptive biochemical systems that would offer flexibility through programmability and autonomous adaptation faces major challenges because of the large number of required chemical species as well as the timing-sensitive feedback loops required for learning. Currently, biochemistry lacks a systems vision on how the user-level programming interface and abstraction with a subsequent translation to chemistry should look like. By developing adaptation in chemistry, we could replace multiple hard-wired systems with a single programmable template that can be (re)trained to …

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Neutron Scattering At The Intersection Of Heart Health Science And Biophysics, Drew Marquardt, Richard J. Alsop, Maikel C. Rheinstädter, Thad A. Harroun Jun 2015

Neutron Scattering At The Intersection Of Heart Health Science And Biophysics, Drew Marquardt, Richard J. Alsop, Maikel C. Rheinstädter, Thad A. Harroun

Chemistry and Biochemistry Publications

There is an urgent quest for improved heart health. Here, we review how neutron radiation can provide insight into the molecular basis of heart health. Lower cholesterol, a daily intake of aspirin and supplemental vitamin E are argued to all improve heart health. However, the mechanisms behind these common regimens, and others, are not entirely understood. It is not clear why a daily intake of aspirin can help some people with heart disease, and the benefits of vitamin E in the treatment of reperfusion injury have been heavily debated. The molecular impact of cholesterol in the body is still a …

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The Evolution Of Scientific Productivity Of Junior Scholars, Chun-Hua Tsai, Yu-Ru Lin Jun 2015

The Evolution Of Scientific Productivity Of Junior Scholars, Chun-Hua Tsai, Yu-Ru Lin

Information Systems and Quantitative Analysis Faculty Proceedings & Presentations

Publishing academic work has been recognized as a key indicator for measuring scholars’ scientific productivity and having crucial impact on their future career. However, little has been known about how the majority of researchers progress in publishing papers across disciplines. In this work, using a collection consisting of over five millions academic publications across 15 disciplines, we study how the scientific productivity patterns of junior scholars change across different generations and different domains. Our study results help understand the evolution of the competitive “publish or perish” academic culture.

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Developing Strategic And Mathematical Thinking Via Game Play: Programming To Investigate A Risky Strategy For Quarto, Peter Rowlett Jun 2015

Developing Strategic And Mathematical Thinking Via Game Play: Programming To Investigate A Risky Strategy For Quarto, Peter Rowlett

The Mathematics Enthusiast

The Maths Arcade is an extracurricular club for undergraduate students to play and analyse strategy board games, aimed at building a mathematical community of staff and students as well as improving strategic and mathematical thinking. This educational initiative, used at several universities in the U.K., will be described. Quarto is an impartial game played at the Maths Arcade, in that there is one set of common pieces used by both players, and one where stalemates are a common outcome. While some students play without apparent direction until a winning opportunity appears, others adopt a more risky strategy of building the …

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