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Spin Model Checker
SPIN is a general tool for verifying the correctness of concurrent software models in a rigorous and mostly automated fashion. It was written by Gerard J. Holzmann and others in the original Unix group of the Computing Sciences Research Center at Bell Labs, beginning in 1980. The software has been available freely since 1991, and continues to evolve to keep pace with new developments in the field. Tool Systems to be verified are described in Promela (Process Meta Language), which supports modeling of asynchronous distributed algorithms as non-deterministic automata (''SPIN'' stands for "Simple Promela Interpreter"). Properties to be verified are expressed as Linear Temporal Logic (LTL) formulas, which are negated and then converted into Büchi automata as part of the model-checking algorithm. In addition to model-checking, SPIN can also operate as a simulator, following one possible execution path through the system and presenting the resulting execution trace to the user. Un ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bitstate Hashing
Bitstate hashing is a hash function, hashing method invented in 1968 by Morris. It is used for state hashing, where each state (e.g. of an automaton) is represented by a number and it is passed to some hash function. The result of the function is then taken as the index to an array of bits (a bit-field), where one looks for 1 if the state was already seen before or stores 1 by itself if not. It usually serves as a yes–no technique without a need of storing whole state bit representation. A shortcoming of this framework is losing precision like in other hashing techniques. Hence some tools use this technique with more than one hash function so that the bit-field gets widened by the number of used functions, each having its own row. And even after all functions return values (the indices) point to fields with contents equal to 1, the state may be uttered as visited with much higher probability. Use * Bitstate hashing is utilized in the SPIN_model_checker, SPIN model checker for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gerard J
Gerard is a masculine forename of Proto-Germanic origin, variations of which exist in many Germanic and Romance languages. Like many other early Germanic names, it is dithematic, consisting of two meaningful constituents put together. In this case, those constituents are ''gari'' > ''ger-'' (meaning 'spear') and -''hard'' (meaning 'hard/strong/brave'). Common forms of the name are Gerard (English, Scottish, Irish, Dutch, Polish and Catalan); Gerrard (English, Scottish, Irish); Gerardo (Italian, and Spanish); Geraldo ( Portuguese); Gherardo (Italian); Gherardi ( Northern Italian, now only a surname); Gérard (variant forms ''Girard'' and ''Guérard'', now only surnames, French); Gearóid ( Irish); Gerhardt and Gerhart/ Gerhard/ Gerhardus (German, Dutch, and Afrikaans); Gellért ( Hungarian); Gerardas ( Lithuanian) and Gerards/Ģirts ( Latvian); Γεράρδης (Greece). A few abbreviated forms are Gerry and Jerry (English); Gerd (German) and Gert (Afrikaans and Dutch); Ge ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Automata Theory
Automata theory is the study of abstract machines and automata, as well as the computational problems that can be solved using them. It is a theory in theoretical computer science. The word ''automata'' comes from the Greek word αὐτόματος, which means "self-acting, self-willed, self-moving". An automaton (automata in plural) is an abstract self-propelled computing device which follows a predetermined sequence of operations automatically. An automaton with a finite number of states is called a Finite Automaton (FA) or Finite-State Machine (FSM). The figure on the right illustrates a finite-state machine, which is a well-known type of automaton. This automaton consists of states (represented in the figure by circles) and transitions (represented by arrows). As the automaton sees a symbol of input, it makes a transition (or jump) to another state, according to its transition function, which takes the previous state and current input symbol as its arguments. Automata theo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uppaal Model Checker
UPPAAL is an integrated tool environment for modeling, validation and verification of real-time systems modeled as networks of timed automata, extended with data types (bounded integers, arrays etc.). It has been used in at least 17 case studies since its release in 1995, including on Lego Mindstorms, for the Philips audio protocol, and in gearbox controllers for Mecel. The tool has been developed in collaboration between the Design and Analysis of Real-Time Systems group at Uppsala University, Sweden and Basic Research in Computer Science at Aalborg University, Denmark ) , song = ( en, "King Christian stood by the lofty mast") , song_type = National and royal anthem , image_map = EU-Denmark.svg , map_caption = , subdivision_type = Sovereign state , subdivision_name = Kingdom of Denmark , establish .... There are the following extensions available: *'Cora'' for Cost Optimal Reachability Analysis. *'Tron'' for Testing Real-time systems ON-line (black-box conforman ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NuSMV
NuSMV is a reimplementation and extension of SMV symbolic model checker, the first model checking tool based on Binary Decision Diagrams (BDDs).K.L. McMillan. Symbolic model checking. In Kluwer Academic Publ.,1993. The tool has been designed as an open architecture for model checking. It is aimed at reliable verification of industrially sized designs, for use as a backend for other verification tools and as a research tool for formal verification techniques. NuSMV has been developed as a joint project between ITC-IRST ( Istituto Trentino di Cultura in Trento, Italy), Carnegie Mellon University, the University of Genoa and the University of Trento. NuSMV 2, version 2 of NuSMV, inherits all the functionalities of NuSMV. Furthermore, it combines BDD-based model checking with SAT-based model checking.A. Biere, A. Cimatti, E. Clarke, and Y. Zhu. Symbolic model checking without BDDs. In Tools and Algorithms for Construction and Analysis of Systems, In TACAS’99, March 1999. It is ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Association For Computing Machinery
The Association for Computing Machinery (ACM) is a US-based international learned society for computing. It was founded in 1947 and is the world's largest scientific and educational computing society. The ACM is a non-profit professional membership group, claiming nearly 110,000 student and professional members . Its headquarters are in New York City. The ACM is an umbrella organization for academic and scholarly interests in computer science ( informatics). Its motto is "Advancing Computing as a Science & Profession". History In 1947, a notice was sent to various people: On January 10, 1947, at the Symposium on Large-Scale Digital Calculating Machinery at the Harvard computation Laboratory, Professor Samuel H. Caldwell of Massachusetts Institute of Technology spoke of the need for an association of those interested in computing machinery, and of the need for communication between them. ..After making some inquiries during May and June, we believe there is ample interest to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Model Checking
In computer science, model checking or property checking is a method for checking whether a finite-state model of a system meets a given specification (also known as correctness). This is typically associated with hardware or software systems, where the specification contains liveness requirements (such as avoidance of livelock) as well as safety requirements (such as avoidance of states representing a system crash). In order to solve such a problem algorithmically, both the model of the system and its specification are formulated in some precise mathematical language. To this end, the problem is formulated as a task in logic, namely to check whether a structure satisfies a given logical formula. This general concept applies to many kinds of logic and many kinds of structures. A simple model-checking problem consists of verifying whether a formula in the propositional logic is satisfied by a given structure. Overview Property checking is used for verification when two d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Completeness (knowledge Bases)
The term completeness as applied to knowledge bases refers to two different concepts. Formal logic In formal logic, a knowledge base KB is complete ''if'' there is no formula α such that KB ⊭ α and KB ⊭ ¬α. Example of knowledge base with incomplete knowledge: KB := Then we have KB ⊭ A and KB ⊭ ¬A. In some cases, a consistent knowledge base can be made complete with the closed world assumption—that is, adding all not-entailed literals as negations to the knowledge base. In the above example though, this would not work because it would make the knowledge base inconsistent: KB' = In the case where KB := , KB ⊭ P(b) and KB ⊭ ¬P(b), so, with the closed world assumption, KB' = , where KB' ⊨ ¬P(b). Data management In data management, completeness is metaknowledge that can be asserted for parts of the KB via completeness assertions. As example, a knowledge base may contain complete information for predicates R and S, while nothing is asserted for predic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Data Compression
In information theory, data compression, source coding, or bit-rate reduction is the process of encoding information using fewer bits than the original representation. Any particular compression is either lossy or lossless. Lossless compression reduces bits by identifying and eliminating statistical redundancy. No information is lost in lossless compression. Lossy compression reduces bits by removing unnecessary or less important information. Typically, a device that performs data compression is referred to as an encoder, and one that performs the reversal of the process (decompression) as a decoder. The process of reducing the size of a data file is often referred to as data compression. In the context of data transmission, it is called source coding; encoding done at the source of the data before it is stored or transmitted. Source coding should not be confused with channel coding, for error detection and correction or line coding, the means for mapping data onto a signal. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Partial Order Reduction
In computer science, partial order reduction is a technique for reducing the size of the state-space to be searched by a model checking or automated planning and scheduling algorithm. It exploits the commutativity of concurrently executed transitions that result in the same state when executed in different orders. In explicit state space exploration, partial order reduction usually refers to the specific technique of expanding a representative subset of all enabled transitions. This technique has also been described as model checking with representatives. There are various versions of the method, the so-called stubborn set method, ample set method, and persistent set method. Ample sets Ample sets are an example of model checking with representatives. Their formulation relies on a separate notion of ''dependency''. Two transitions are considered independent only if whenever they are mutually enabled, they cannot disable another and the execution of both results in a unique state ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Büchi Automaton
In computer science and automata theory, a deterministic Büchi automaton is a theoretical machine which either accepts or rejects infinite inputs. Such a machine has a set of states and a transition function, which determines which state the machine should move to from its current state when it reads the next input character. Some states are accepting states and one state is the start state. The machine accepts an input if and only if it will pass through an accepting state infinitely many times as it reads the input. A non-deterministic Büchi automaton, later referred to just as a Büchi automaton, has a transition function which may have multiple outputs, leading to many possible paths for the same input; it accepts an infinite input if and only if some possible path is accepting. Deterministic and non-deterministic Büchi automata generalize deterministic finite automata and nondeterministic finite automata to infinite inputs. Each are types of ω-automata. Büchi automata r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linear Temporal Logic
In logic, linear temporal logic or linear-time temporal logic (LTL) is a modal temporal logic with modalities referring to time. In LTL, one can encode formulae about the future of paths, e.g., a condition will eventually be true, a condition will be true until another fact becomes true, etc. It is a fragment of the more complex CTL*, which additionally allows branching time and quantifiers. Subsequently, LTL is sometimes called ''propositional temporal logic'', abbreviated ''PTL''. In terms of expressive power, linear temporal logic (LTL) is a fragment of first-order logic. LTL was first proposed for the formal verification of computer programs by Amir Pnueli in 1977. Syntax LTL is built up from a finite set of propositional variables ''AP'', the logical operators ¬ and ∨, and the temporal modal operators X (some literature uses O or N) and U. Formally, the set of LTL formulas over ''AP'' is inductively defined as follows: * if p ∈ ''AP'' then p is an LTL formula; * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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