Redexes are stable in the λ-calculus

2015 ◽  
Vol 27 (5) ◽  
pp. 738-750 ◽  
Author(s):  
JEAN-JACQUES LÉVY
Keyword(s):  
Programming Languages ◽  
Programming Language ◽  
Stability Property ◽  
Lambda Calculus ◽  
Unique Minimum ◽  
Sequential Programming ◽  
The Stability

In the theory of sequential programming languages, Berry's stability property is an important step claiming that values have unique origins in their calculations. It has been shown that Bohm trees are stable in the λ-calculus, meaning that there is a unique minimum prefix of any lambda term which computes its Bohm tree. Moreover this property is also true for finite prefixes of Bohm trees. The proof relies on Curry's standardization theorem as initially pointed out by Plotkin in his famous articleLCF considered as a programming language. In this paper we will show that the stability property also holds for redexes. Namely for any redex family, there is a unique minimum calculation and a unique redex which computes this family. This property was already known in the study of optimal reductions, but we stress here on stability and want to show that stability is inside the basic objects of calculations. The proof will be based on nice commutations between residuals and creations of new redexes. Our tool for proving this property will be the labelled lambda calculus used in the study of optimal reductions.

PERANGKAT LUNAK KOMPUTER

2020 ◽  
Author(s):  
Cut Nabilah Damni
Keyword(s):  
Programming Languages ◽  
Programming Language ◽  
Operating Systems ◽  
Source Code ◽  
Computer Software ◽  
Computer Programs ◽  
Application Systems ◽  
Executable Programs

AbstrakSoftware komputer atau perangkat lunak komputer merupakan kumpulan instruksi (program atau prosedur) untuk dapat melaksanakan pekerjaan secara otomatis dengan cara mengolah atau memproses kumpulan intruksi (data) yang diberikan. (Yahfizham, 2019 : 19) Sebagian besar dari software komputer dibuat oleh (programmer) dengan menggunakan bahasa pemprograman. Orang yang membuat bahasa pemprograman menuliskan perintah dalam bahasa pemprograman seperti layaknya bahasa yang digunakan oleh orang pada umumnya dalam melakukan perbincangan. Perintah-perintah tersebut dinamakan (source code). Program komputer lainnya dinamakan (compiler) yang digunakan pada (source code) dan kemudian mengubah perintah tersebut kedalam bahasa yang dimengerti oleh komputer lalu hasilnya dinamakan program executable (EXE). Pada dasarnya, komputer selalu memiliki perangkat lunak komputer atau software yang terdiri dari sistem operasi, sistem aplikasi dan bahasa pemograman.AbstractComputer software or computer software is a collection of instructions (programs or procedures) to be able to carry out work automatically by processing or processing the collection of instructions (data) provided. (Yahfizham, 2019: 19) Most of the computer software is made by (programmers) using the programming language. People who make programming languages write commands in the programming language like the language used by people in general in conducting conversation. The commands are called (source code). Other computer programs called (compilers) are used in (source code) and then change the command into a language understood by the computer and the results are called executable programs (EXE). Basically, computers always have computer software or software consisting of operating systems, application systems and programming languages.

Coupled Stability of Multiport Systems—Theory and Experiments

1994 ◽  
Vol 116 (3) ◽  
pp. 419-428 ◽  
Author(s):  
J. E. Colgate
Keyword(s):  
Stability Property ◽  
Force Feedback ◽  
Linear Time ◽  
Experimental Studies ◽  
Sufficient Conditions ◽  
Direct Drive ◽  
Property A ◽  
Linear Time Invariant ◽  
The Stability ◽  
Necessary And Sufficient

This paper presents both theoretical and experimental studies of the stability of dynamic interaction between a feedback controlled manipulator and a passive environment. Necessary and sufficient conditions for “coupled stability”—the stability of a linear, time-invariant n-port (e.g., a robot, linearized about an operating point) coupled to a passive, but otherwise arbitrary, environment—are presented. The problem of assessing coupled stability for a physical system (continuous time) with a discrete time controller is then addressed. It is demonstrated that such a system may exhibit the coupled stability property; however, analytical, or even inexpensive numerical conditions are difficult to obtain. Therefore, an approximate condition, based on easily computed multivariable Nyquist plots, is developed. This condition is used to analyze two controllers implemented on a two-link, direct drive robot. An impedance controller demonstrates that a feedback controlled manipulator may satisfy the coupled stability property. A LQG/LTR controller illustrates specific consequences of failure to meet the coupled stability criterion; it also illustrates how coupled instability may arise in the absence of force feedback. Two experimental procedures—measurement of endpoint admittance and interaction with springs and masses—are introduced and used to evaluate the above controllers. Theoretical and experimental results are compared.

scholarly journals Hybrid Java: The creation of a Hybrid Programming Environment

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Mark Noone ◽  
Aidan Mooney ◽  
Keith Nolan
Keyword(s):  
Programming Languages ◽  
Programming Language ◽  
Visual Programming ◽  
First Year ◽  
Programming Environment ◽  
Programming Environments ◽  
Hybrid Programming ◽  
Java Language ◽  
The Creation ◽  
Visual Programming Language

This article details the creation of a hybrid computer programming environment combining the power of the text-based Java language with the visual features of the Snap! language. It has been well documented that there exists a gap in the education of computing students in their mid-to-late teenage years, where perhaps visual programming languages are no longer suitable and textual programming languages may involve too steep of a learning curve. There is an increasing need for programming environments that combine the benefits of both languages into one. Snap! is a visual programming language which employs “blocks” to allow users to build programs, similar to the functionality offered by Scratch. One added benefit of Snap! is that it offers the ability to create one’s own blocks and extend the functionality of those blocks to create more complex and powerful programs. This will be utilised to create the Hybrid Java environment. The development of this tool will be detailed in the article, along with the motivation and use cases for it. Initial testing conducted will be discussed including one phase that gathered feedback from a pool of 174 first year Computer Science students. These participants were given instructions to work with the hybrid programming language and evaluate their experience of using it. The analysis of the findings along with future improvements to the language will also be presented.

scholarly journals An Abstract Contract Theory for Programs with Procedures

2021 ◽  
pp. 152-171
Author(s):  
Christian Lidström ◽  
Dilian Gurov
Keyword(s):  
Programming Languages ◽  
Contract Theory ◽  
Denotational Semantics ◽  
The Other ◽  
Hoare Logic ◽  
Basic Building Block ◽  
Sequential Programming ◽  
Modular Verification ◽  
The One ◽  
Meta Theory

AbstractWhen developing complex software and systems, contracts provide a means for controlling the complexity by dividing the responsibilities among the components of the system in a hierarchical fashion. In specific application areas, dedicated contract theories formalise the notion of contract and the operations on contracts in a manner that supports best the development of systems in that area. At the other end, contract meta-theories attempt to provide a systematic view on the various contract theories by axiomatising their desired properties. However, there exists a noticeable gap between the most well-known contract meta-theory of Benveniste et al. [5], which focuses on the design of embedded and cyber-physical systems, and the established way of using contracts when developing general software, following Meyer’s design-by-contract methodology [18]. At the core of this gap appears to be the notion of procedure: while it is a central unit of composition in software development, the meta-theory does not suggest an obvious way of treating procedures as components.In this paper, we provide a first step towards a contract theory that takes procedures as the basic building block, and is at the same time an instantiation of the meta-theory. To this end, we propose an abstract contract theory for sequential programming languages with procedures, based on denotational semantics. We show that, on the one hand, the specification of contracts of procedures in Hoare logic, and their procedure-modular verification, can be cast naturally in the framework of our abstract contract theory. On the other hand, we also show our contract theory to fulfil the axioms of the meta-theory. In this way, we give further evidence for the utility of the meta-theory, and prepare the ground for combining our instantiation with other, already existing instantiations.

scholarly journals Learners Programming Language a Helping System for Introductory Programming Courses

2016 ◽  
Vol 35 (3) ◽  
pp. 347-358
Author(s):  
Muhammad Shumail Naveed ◽  
Muhammad Sarim ◽  
Kamran Ahsan
Keyword(s):  
Programming Languages ◽  
Programming Language ◽  
Retention Rate ◽  
Introductory Programming ◽  
Source Program ◽  
Definition Of ◽  
High Level ◽  
Novice Students ◽  
Introductory Programming Courses ◽  
Programming Courses

Programming is the core of computer science and due to this momentousness a special care is taken in designing the curriculum of programming courses. A substantial work has been conducted on the definition of programming courses, yet the introductory programming courses are still facing high attrition, low retention and lack of motivation. This paper introduced a tiny pre-programming language called LPL (Learners Programming Language) as a ZPL (Zeroth Programming Language) to illuminate novice students about elementary concepts of introductory programming before introducing the first imperative programming course. The overall objective and design philosophy of LPL is based on a hypothesis that the soft introduction of a simple and paradigm specific textual programming can increase the motivation level of novice students and reduce the congenital complexities and hardness of the first programming course and eventually improve the retention rate and may be fruitful in reducing the dropout/failure level. LPL also generates the equivalent high level programs from user source program and eventually very fruitful in understanding the syntax of introductory programming languages. To overcome the inherent complexities of unusual and rigid syntax of introductory programming languages, the LPL provide elementary programming concepts in the form of algorithmic and plain natural language based computational statements. The initial results obtained after the introduction of LPL are very encouraging in motivating novice students and improving the retention rate.

scholarly journals Tree-Shaped Formats of Address Programming Language

2021 ◽  
Vol 4 ◽  
pp. 78-87
Author(s):  
Yury Yuschenko
Keyword(s):  
Programming Languages ◽  
Programming Language ◽  
Theoretical Research ◽  
Direct Access ◽  
Complex Data ◽  
Abstract Data Types ◽  
Data Types ◽  
Abstract Data ◽  
The One ◽  
High Level

In the Address Programming Language (1955), the concept of indirect addressing of higher ranks (Pointers) was introduced, which allows the arbitrary connection of the computer’s RAM cells. This connection is based on standard sequences of the cell addresses in RAM and addressing sequences, which is determined by the programmer with indirect addressing. Two types of sequences allow programmers to determine an arbitrary connection of RAM cells with the arbitrary content: data, addresses, subroutines, program labels, etc. Therefore, the formed connections of cells can relate to each other. The result of connecting cells with the arbitrary content and any structure is called tree-shaped formats. Tree-shaped formats allow programmers to combine data into complex data structures that are like abstract data types. For tree-shaped formats, the concept of “review scheme” is defined, which is like the concept of “bypassing” trees. Programmers can define multiple overview diagrams for the one tree-shaped format. Programmers can create tree-shaped formats over the connected cells to define the desired overview schemes for these connected cells. The work gives a modern interpretation of the concept of tree-shaped formats in Address Programming. Tree-shaped formats are based on “stroke-operation” (pointer dereference), which was hardware implemented in the command system of computer “Kyiv”. Group operations of modernization of computer “Kyiv” addresses accelerate the processing of tree-shaped formats and are designed as organized cycles, like those in high-level imperative programming languages. The commands of computer “Kyiv”, due to operations with indirect addressing, have more capabilities than the first high-level programming language – Plankalkül. Machine commands of the computer “Kyiv” allow direct access to the i-th element of the “list” by its serial number in the same way as such access is obtained to the i-th element of the array by its index. Given examples of singly linked lists show the features of tree-shaped formats and their differences from abstract data types. The article opens a new branch of theoretical research, the purpose of which is to analyze the expe- diency of partial inclusion of Address Programming in modern programming languages.

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