scholarly journals Gradually structured data

2021 ◽  
Vol 5 (OOPSLA) ◽  
pp. 1-29
Author(s):  
Stefan Malewski ◽  
Michael Greenberg ◽  
Éric Tanter
Keyword(s):  
Ad Hoc ◽  
Structured Data ◽  
Computational Aspect ◽  
Type Safety ◽  
Novel Approach ◽  
Dynamic Languages ◽  
Gradual Typing ◽  
Static Checking ◽  
Server Application ◽  
Typed Languages

Dynamically-typed languages offer easy interaction with ad hoc data such as JSON and S-expressions; statically-typed languages offer powerful tools for working with structured data, notably algebraic datatypes , which are a core feature of typed languages both functional and otherwise. Gradual typing aims to reconcile dynamic and static typing smoothly. The gradual typing literature has extensively focused on the computational aspect of types, such as type safety, effects, noninterference, or parametricity, but the application of graduality to data structuring mechanisms has been much less explored. While row polymorphism and set-theoretic types have been studied in the context of gradual typing, algebraic datatypes in particular have not, which is surprising considering their wide use in practice. We develop, formalize, and prototype a novel approach to gradually structured data with algebraic datatypes. Gradually structured data bridges the gap between traditional algebraic datatypes and flexible data management mechanisms such as tagged data in dynamic languages, or polymorphic variants in OCaml. We illustrate the key ideas of gradual algebraic datatypes through the evolution of a small server application from dynamic to progressively more static checking, formalize a core functional language with gradually structured data, and establish its metatheory, including the gradual guarantees.

scholarly journals A Novel Approach for Reliable Route Discovery in Mobile Ad-Hoc Network

2015 ◽  
Vol 83 (2) ◽  
pp. 1519-1529 ◽  
Author(s):  
Shariq Mahmood Khan ◽  
R. Nilavalan ◽  
Abdulhafid F. Sallama
Keyword(s):  
Ad Hoc Network ◽  
Ad Hoc ◽  
Mobile Ad Hoc Network ◽  
Route Discovery ◽  
Novel Approach ◽  
Mobile Ad Hoc

scholarly journals Shearlet-based regularized reconstruction in region-of-interest computed tomography

2018 ◽  
Vol 13 (4) ◽  
pp. 34
Author(s):  
T.A. Bubba ◽  
D. Labate ◽  
G. Zanghirati ◽  
S. Bonettini
Keyword(s):  
Optimization Problem ◽  
Ad Hoc ◽  
Iterative Scheme ◽  
Tomographic Reconstruction ◽  
Region Of Interest ◽  
Projection Data ◽  
Reconstruction Problem ◽  
Convex Optimization Problem ◽  
Scanning Time ◽  
Novel Approach

Region of interest (ROI) tomography has gained increasing attention in recent years due to its potential to reducing radiation exposure and shortening the scanning time. However, tomographic reconstruction from ROI-focused illumination involves truncated projection data and typically results in higher numerical instability even when the reconstruction problem has unique solution. To address this problem, bothad hocanalytic formulas and iterative numerical schemes have been proposed in the literature. In this paper, we introduce a novel approach for ROI tomographic reconstruction, formulated as a convex optimization problem with a regularized term based on shearlets. Our numerical implementation consists of an iterative scheme based on the scaled gradient projection method and it is tested in the context of fan-beam CT. Our results show that our approach is essentially insensitive to the location of the ROI and remains very stable also when the ROI size is rather small.

scholarly journals How to make ad hoc proof automation less ad hoc

2013 ◽  
Vol 23 (4) ◽  
pp. 357-401 ◽  
Author(s):  
GEORGES GONTHIER ◽  
BETA ZILIANI ◽  
ALEKSANDAR NANEVSKI ◽  
DEREK DREYER
Keyword(s):  
Design Patterns ◽  
Ad Hoc ◽  
Type System ◽  
Type Inference ◽  
Interactive Theorem Provers ◽  
Proof Automation ◽  
Novel Approach ◽  
Type Classes ◽  
Structure Programming ◽  
Base Logic

AbstractMost interactive theorem provers provide support for some form of user-customizable proof automation. In a number of popular systems, such as Coq and Isabelle, this automation is achieved primarily through tactics, which are programmed in a separate language from that of the prover's base logic. While tactics are clearly useful in practice, they can be difficult to maintain and compose because, unlike lemmas, their behavior cannot be specified within the expressive type system of the prover itself.We propose a novel approach to proof automation in Coq that allows the user to specify the behavior of custom automated routines in terms of Coq's own type system. Our approach involves a sophisticated application of Coq's canonical structures, which generalize Haskell type classes and facilitate a flexible style of dependently-typed logic programming. Specifically, just as Haskell type classes are used to infer the canonical implementation of an overloaded term at a given type, canonical structures can be used to infer the canonical proof of an overloaded lemma for a given instantiation of its parameters. We present a series of design patterns for canonical structure programming that enable one to carefully and predictably coax Coq's type inference engine into triggering the execution of user-supplied algorithms during unification, and we illustrate these patterns through several realistic examples drawn from Hoare Type Theory. We assume no prior knowledge of Coq and describe the relevant aspects of Coq type inference from first principles.

Measuring mono-word termhood by rank difference via corpus comparison

Terminology ◽  
2008 ◽  
Vol 14 (2) ◽  
pp. 204-229 ◽  
Author(s):  
Chunyu Kit ◽  
Xiaoyue Liu
Keyword(s):  
Ad Hoc ◽  
Critical Role ◽  
Novel Approach ◽  
Rank Difference ◽  
Special Knowledge ◽  
British National Corpus ◽  
Automatic Term Recognition ◽  
Core Issues ◽  
Term Candidate ◽  
National Corpus

Terminology as a set of concept carriers crystallizes our special knowledge about a subject. Automatic term recognition (ATR) plays a critical role in the processing and management of various kinds of information, knowledge and documents, e.g., knowledge acquisition via text mining. Measuring termhood properly is one of the core issues involved in ATR. This article presents a novel approach to termhood measurement for mono-word terms via corpus comparison, which quantifies the termhood of a term candidate as its rank difference in a domain and a background corpus. Our ATR experiments to identify legal terms in Hong Kong (HK) legal texts with the British National Corpus (BNC) as background corpus provide evidence to confirm the validity and effectiveness of this approach. Without any prior knowledge and ad hoc heuristics, it achieves a precision of 97.0% on the top 1000 candidates and a precision of 96.1% on the top 10% candidates that are most highly ranked by the termhood measure, illustrating a state-of-the-art performance on mono-word ATR in the field.

Interactive Models for Virtual Enterprises

2011 ◽  
pp. 316-333
Author(s):  
Håvard D. Jorgensen ◽  
John Krogstie
Keyword(s):  
Case Studies ◽  
Ad Hoc ◽  
Virtual Enterprises ◽  
Major Result ◽  
Research Projects ◽  
Model Driven ◽  
Visual Model ◽  
Novel Approach ◽  
Interactive Models ◽  
And Performance

This chapter presents a novel approach to the development, integration, and operation of virtual enterprises (VEs). The approach is based on the idea of interactive models. An interactive model is a visual model of enterprise aspects that can be viewed, traversed, analyzed, simulated, adapted, and executed by the participants of the VE. The approach has been developed in several research projects, where experiences from industrial case studies are used as a basis for validation and further enhancement. A major result of this work is the model-driven infrastructure that integrates and supports VEs. The main innovative contributions of this infrastructure include concurrent modelling, metamodelling, management and performance of work, integrated support for ad hoc and structured processes, and customizable model- and process-driven integration.

Sound and complete models of contracts

2006 ◽  
Vol 16 (4-5) ◽  
pp. 375-414 ◽  
Author(s):  
MATTHIAS BLUME ◽  
DAVID McALLESTER
Keyword(s):  
Ad Hoc ◽  
Expressive Power ◽  
Higher Order ◽  
Original Version ◽  
Order Types ◽  
Restricted Form ◽  
Soundness And Completeness ◽  
Recursive Contracts ◽  
Intuitive Interpretation ◽  
Typed Languages

Even in statically typed languages it is useful to have certain invariants checked dynamically. Findler and Felleisen gave an algorithm for dynamically checking expressive higher-order types called contracts. They did not, however, give a semantics of contracts. The lack of a semantics makes it impossible to define and prove soundness and completeness of the checking algorithm. (Given a semantics, a sound checker never reports violations that do not exist under that semantics; a complete checker is – in principle – able to find violations when violations exist.) Ideally, a semantics should capture what programmers intuitively feel is the meaning of a contract or otherwise clearly point out where intuition does not match reality. In this paper we give an interpretation of contracts for which we prove the Findler-Felleisen algorithm sound and (under reasonable assumptions) complete. While our semantics mostly matches intuition, it also exposes a problem with predicate contracts where an arguably more intuitive interpretation than ours would render the checking algorithm unsound. In our semantics we have to make use of a notion of safety (which we define in the paper) to avoid unsoundness. We are able to eliminate the “leakage” of safety into the semantics by changing the language, replacing the original version of unrestricted predicate contracts with a restricted form. The corresponding loss in expressive power can be recovered by making safety explicit as a contract. This can be done either in ad-hoc fashion or by including general recursive contracts. The addition of recursive contracts has far-reaching implications, deeply affecting the formulation of our model and requiring different techniques for proving soundness.

UbiSrvInt

2009 ◽  
pp. 135-171
Author(s):  
Soe-Tsyr Yuan ◽  
Fang-Yu Chen
Keyword(s):  
Service Provision ◽  
Ad Hoc ◽  
Fault Tolerant ◽  
Service Needs ◽  
Novel Approach ◽  
Distributed Problem Solving ◽  
Wireless Service ◽  
Wireless Environments ◽  
P2p Applications ◽  
Performance Results

Peer-to-Peer applications harness sharing between free resources (storage, contents, services, human presence, etc.). Most existing wireless P2P applications concern merely the sharing of a variety of contents. For magnifying the sharing extent for wireless service provision in the vicinity (i.e., the wireless P2P environments), this chapter presents a novel approach (briefly named UbiSrvInt) that is an attempt to enable a pure P2P solution that is context aware and fault tolerant for ad-hoc wireless service provision. This approach empowers an autonomous peer to propel distributed problem solving (e.g., in the travel domain) through service sharing and execution in an intelligent P2P way. This approach of ad-hoc wireless service provision is not only highly robust to failure (based on a specific clustering analysis of failure correlation among peers) but also capable of inferring a user’s service needs (through a BDI reasoning mechanism utilizing the surrounding context) in ad-hoc wireless environments. The authors have implemented UbiSrvInt into a system platform with P-JXTA that shows good performance results on fault tolerance and context awareness.

Sign in / Sign up

Export Citation Format

Share Document