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Program Derivation
In computer science, program derivation is the derivation of a program from its specification, by mathematical means. To ''derive'' a program means to write a formal specification, which is usually non-executable, and then apply mathematically correct rules in order to obtain an executable program satisfying that specification. The program thus obtained is then correct by construction. Program and correctness proof are constructed together. The approach usually taken in formal verification is to first write a program, and then provide a proof that it conforms to a given specification. The main problems with this are that: * the resulting proof is often long and cumbersome; * no insight is given as to how the program was developed; it appears "like a rabbit out of a hat"; * should the program happen to be incorrect in some subtle way, the attempt to verify it is likely to be long and certain to be fruitless. Program derivation tries to remedy these shortcomings by: * keeping proo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Science
Computer science is the study of computation, information, and automation. Computer science spans Theoretical computer science, theoretical disciplines (such as algorithms, theory of computation, and information theory) to Applied science, applied disciplines (including the design and implementation of Computer architecture, hardware and Software engineering, software). Algorithms and data structures are central to computer science. The theory of computation concerns abstract models of computation and general classes of computational problem, problems that can be solved using them. The fields of cryptography and computer security involve studying the means for secure communication and preventing security vulnerabilities. Computer graphics (computer science), Computer graphics and computational geometry address the generation of images. Programming language theory considers different ways to describe computational processes, and database theory concerns the management of re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Automatic Programming
In computer science, automatic programming is a type of computer programming in which some mechanism generates a computer program, to allow human programmers to write the code at a higher abstraction level. There has been little agreement on the precise definition of automatic programming, mostly because its meaning has changed over time. David Parnas, tracing the history of "automatic programming" in published research, noted that in the 1940s it described automation of the manual process of punching paper tape. Later it referred to translation of high-level programming languages like Fortran and ALGOL. In fact, one of the earliest programs identifiable as a compiler was called Autocode. David Parnas, Parnas concluded that "automatic programming has always been a euphemism for programming in a higher-level language than was then available to the programmer." Program synthesis is one type of automatic programming where a procedure is created from scratch, based on mathematical req ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carroll Morgan (computer Scientist)
Charles ''Carroll'' Morgan (born 1952) is an American computer scientist who moved to Australia in his early teens. He completed his education there (high school, university, several years in industry), including a Doctor of Philosophy (Ph.D.) degree from the University of Sydney, and then moved to the United Kingdom in the early 1980s. In 2000, he returned to Australia. During the 1980s and 1990s, Morgan was based at the Oxford University Computing Laboratory in England as a researcher and lecturer working in the area of formal methods, and was a Fellow of Pembroke College. Having been influenced by the Z notation of Jean-Raymond Abrial, he authored ''Programming from Specifications'' as an attempt to combine the high-level specification aspects of Z, with the rigorous computer program derivation methods of Edsger W. Dijkstra. His treatment concentrated on elementary program constructs to make the material accessible to undergraduates in their early years. Some of the ideas ther ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proof-carrying Code
Proof-carrying code (PCC) is a software mechanism that allows a host system to verify properties about an application via a formal proof that accompanies the application's executable code. The host system can quickly verify the validity of the proof, and it can compare the conclusions of the proof to its own security policy to determine whether the application is safe to execute. This can be particularly useful in ensuring memory safety (i.e. preventing issues like buffer overflows). Proof-carrying code was originally described in 1996 by George Necula and Peter Lee. Packet filter example The original publication on proof-carrying code in 1996Necula, G. C. and Lee, P. 1996. Safe kernel extensions without run-time checking. SIGOPS Operating Systems Review 30, SI (Oct. 1996), 229–243. used packet filters as an example: a user-mode application hands a function written in machine code to the kernel that determines whether or not an application is interested in processing a pa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Program Synthesis
In computer science, program synthesis is the task to construct a computer program, program that provably correct, provably satisfies a given high-level formal specification. In contrast to program verification, the program is to be constructed rather than given; however, both fields make use of formal proof techniques, and both comprise approaches of different degrees of automation. In contrast to automatic programming techniques, specifications in program synthesis are usually non-algorithmic statements in an appropriate formal system, logical calculus. The primary application of program synthesis is to relieve the programmer of the burden of writing correct, efficient code that satisfies a specification. However, program synthesis also has applications to superoptimization and inference of loop invariants. Origin During the Summer Institute of Symbolic Logic at Cornell University in 1957, Alonzo Church defined the problem to synthesize a circuit from mathematical requirements. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Design By Contract
Design by contract (DbC), also known as contract programming, programming by contract and design-by-contract programming, is an approach for designing software. It prescribes that software designers should define formal, precise and verifiable interface specifications for software components, which extend the ordinary definition of abstract data types with preconditions, postconditions and invariants. These specifications are referred to as "contracts", in accordance with a conceptual metaphor with the conditions and obligations of business contracts. The DbC approach assumes all ''client components'' that invoke an operation on a ''server component'' will meet the preconditions specified as required for that operation. Where this assumption is considered too risky (as in multi-channel or distributed computing), the inverse approach is taken, meaning that the ''server component'' tests that all relevant preconditions hold true (before, or while, processing the ''client co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Program Refinement
Refinement is a generic term of computer science that encompasses various approaches for producing correct computer programs and simplifying existing programs to enable their formal verification. Program refinement In formal methods, program refinement is the verifiable transformation of an ''abstract'' (high-level) formal specification into a ''concrete'' (low-level) executable program. '' Stepwise refinement'' allows this process to be done in stages. Logically, refinement normally involves implication, but there can be additional complications. The progressive just-in-time preparation of the product backlog (requirements list) in agile software development approaches, such as Scrum, is also commonly described as refinement. Data refinement Data refinement is used to convert an abstract data model (in terms of sets for example) into implementable data structures (such as arrays). Operation refinement converts a specification of an operation on a system into an implementab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hoare Logic
Hoare logic (also known as Floyd–Hoare logic or Hoare rules) is a formal system with a set of logical rules for reasoning rigorously about the correctness of computer programs. It was proposed in 1969 by the British computer scientist and logician Tony Hoare, and subsequently refined by Hoare and other researchers. The original ideas were seeded by the work of Robert W. Floyd, who had published a similar system for flowcharts. Hoare triple The central feature of Hoare logic is the Hoare triple. A triple describes how the execution of a piece of code changes the state of the computation. A Hoare triple is of the form : \ C \ where P and Q are '' assertions'' and C is a ''command''.Hoare originally wrote "P\Q" rather than "\C\". P is named the '' precondition'' and Q the '' postcondition'': when the precondition is met, executing the command establishes the postcondition. Assertions are formulae in predicate logic. Hoare logic provides axioms and inference rules for all ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
P (programming Language)
P is a programming language for asynchronous event-driven programming and the IoT that was developed by Microsoft and University of California, Berkeley. P enables programmers to specify systems consisting of a collection of state machines that communicate asynchronously in terms of events. P programs can run and be analyzed on any platform supported by .NET. Additionally, P programs can generate C# and C code. P is open source, licensed under MIT License, and available on GitHub. Example machine BankServer See also * Microsoft Research * Free software movement References Further reading * P: Safe asynchronous event-driven programming. Ankush Desai, Vivek Gupta, Ethan Jackson, Shaz Qadeer, Sriram Rajamani, and Damien Zufferey. In Proceedings of ACM SIGPLAN Conference on Programming Language Design and Implementation (PLDI), 2013. * Systematic testing of asynchronous reactive systems. Ankush Desai, Shaz Qadeer, and Sanjit A. Seshia. In Proceedings of the 2015 1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Formal Specification
In computer science, formal specifications are mathematically based techniques whose purpose is to help with the implementation of systems and software. They are used to describe a system, to analyze its behavior, and to aid in its design by verifying key properties of interest through rigorous and effective reasoning tools. These specifications are ''formal'' in the sense that they have a syntax, their semantics fall within one domain, and they are able to be used to infer useful information. Motivation In each passing decade, computer systems have become increasingly more powerful and, as a result, they have become more impactful to society. Because of this, better techniques are needed to assist in the design and implementation of reliable software. Established engineering disciplines use mathematical analysis as the foundation of creating and validating product design. Formal specifications are one such way to achieve this in software engineering reliability as once predicted. O ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Distributed Computing
Distributed computing is a field of computer science that studies distributed systems, defined as computer systems whose inter-communicating components are located on different networked computers. The components of a distributed system communicate and coordinate their actions by passing messages to one another in order to achieve a common goal. Three significant challenges of distributed systems are: maintaining concurrency of components, overcoming the lack of a global clock, and managing the independent failure of components. When a component of one system fails, the entire system does not fail. Examples of distributed systems vary from SOA-based systems to microservices to massively multiplayer online games to peer-to-peer applications. Distributed systems cost significantly more than monolithic architectures, primarily due to increased needs for additional hardware, servers, gateways, firewalls, new subnets, proxies, and so on. Also, distributed systems are prone to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
