30,389 research outputs found
Type-based Dependency Analysis for JavaScript
Dependency analysis is a program analysis that determines potential data flow
between program points. While it is not a security analysis per se, it is a
viable basis for investigating data integrity, for ensuring confidentiality,
and for guaranteeing sanitization. A noninterference property can be stated and
proved for the dependency analysis. We have designed and implemented a
dependency analysis for JavaScript. We formalize this analysis as an
abstraction of a tainting semantics. We prove the correctness of the tainting
semantics, the soundness of the abstraction, a noninterference property, and
the termination of the analysis.Comment: Technical Repor
Termination Casts: A Flexible Approach to Termination with General Recursion
This paper proposes a type-and-effect system called Teqt, which distinguishes
terminating terms and total functions from possibly diverging terms and partial
functions, for a lambda calculus with general recursion and equality types. The
central idea is to include a primitive type-form "Terminates t", expressing
that term t is terminating; and then allow terms t to be coerced from possibly
diverging to total, using a proof of Terminates t. We call such coercions
termination casts, and show how to implement terminating recursion using them.
For the meta-theory of the system, we describe a translation from Teqt to a
logical theory of termination for general recursive, simply typed functions.
Every typing judgment of Teqt is translated to a theorem expressing the
appropriate termination property of the computational part of the Teqt term.Comment: In Proceedings PAR 2010, arXiv:1012.455
Operational Semantics of Resolution and Productivity in Horn Clause Logic
This paper presents a study of operational and type-theoretic properties of
different resolution strategies in Horn clause logic. We distinguish four
different kinds of resolution: resolution by unification (SLD-resolution),
resolution by term-matching, the recently introduced structural resolution, and
partial (or lazy) resolution. We express them all uniformly as abstract
reduction systems, which allows us to undertake a thorough comparative analysis
of their properties. To match this small-step semantics, we propose to take
Howard's System H as a type-theoretic semantic counterpart. Using System H, we
interpret Horn formulas as types, and a derivation for a given formula as the
proof term inhabiting the type given by the formula. We prove soundness of
these abstract reduction systems relative to System H, and we show completeness
of SLD-resolution and structural resolution relative to System H. We identify
conditions under which structural resolution is operationally equivalent to
SLD-resolution. We show correspondence between term-matching resolution for
Horn clause programs without existential variables and term rewriting.Comment: Journal Formal Aspect of Computing, 201
PReMo : An Analyzer for P robabilistic Re cursive Mo dels
This paper describes PReMo, a tool for analyzing Recursive Markov Chains, and their controlled/game extensions: (1-exit) Recursive Markov Decision Processes and Recursive Simple Stochastic Games
A distributed Real-Time Java system based on CSP
CSP is a fundamental concept for developing software for distributed real time systems. The CSP paradigm constitutes a natural addition to object orientation and offers higher order multithreading constructs. The CSP channel concept that has been implemented in Java deals with single- and multi-processor environments and also takes care of the real time priority scheduling requirements. For this, the notion of priority and scheduling has been carefully examined and as a result it was reasoned that priority scheduling should be attached to the communicating channels rather than to the processes. In association with channels, a priority based parallel construct is developed for composing processes: hiding threads and priority indexing from the user. This approach simplifies the use of priorities for the object oriented paradigm. Moreover, in the proposed system, the notion of scheduling is no longer connected to the operating system but has become part of the application instead
Transition-Metal Pentatelluride ZrTe and HfTe: a Paradigm for Large-gap Quantum Spin Hall Insulators
Quantum spin Hall (QSH) insulators, a new class of quantum matters, can
support topologically protected helical edge modes inside bulk insulating gap,
which can lead to dissipationless transport. A major obstacle to reach wide
application of QSH is the lack of suitable QSH compounds, which should be
easily fabricated and has large size of bulk gap. Here we predict that single
layer ZrTe and HfTe are the most promising candidates to reach the
large gap QSH insulators with bulk direct (indirect) band gap as large as 0.4
eV (0.1 eV), and robust against external strains. The 3D crystals of these two
materials are good layered compounds with very weak inter-layer bonding and are
located near the phase boundary between weak and strong topological insulators,
which pave a new way to future experimental studies on both QSH effect and
topological phase transitions.Comment: 16 pages, 6 figure
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