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Explore the people, places, events, achievements, struggles and stories that shaped our journey.
Movements, leaders, victories and the continuing fight for equality.
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Pioneers, champions, Negro Leagues, records, activism and excellence.
Meet the people whose lives, choices and achievements shaped the journey.
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Katherine Johnson’s mathematical calculations helped guide some of America’s most important early space missions while she confronted the racial and gender barriers faced by Black women in twentieth-century America.
MORE →Reflects the personal views, recollections, and perspective of the author, Mike Davis.
This is a personal recollection on the Move fire on May 13, 1985
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A specification language is a formal language in computer science used during systems analysis, requirements analysis, and systems design to describe a system at a much higher level than a programming language, which is used to produce the executable code for a system.[1]
Specification languages are generally not directly executed. They are meant to describe the what, not the how.[2] It is considered an error if a requirement specification is cluttered with unnecessary implementation detail.
A common fundamental assumption of many specification approaches is that programs are modelled as algebraic or model-theoretic structures that include a collection of sets of data values together with functions over those sets. This level of abstraction coincides with the view that the correctness of the input/output behaviour of a program takes precedence over all its other properties.
In the property-oriented approach to specification (taken, e.g., by CASL), specifications of programs consist mainly of logical axioms, usually in a logical system in which equality has a prominent role, describing the properties that the functions are required to satisfy—often just by their interrelationship. This is in contrast to so-called model-oriented specification in frameworks like VDM and the Z notation, which consist of a simple realization of the required behaviour.
Specifications must be subject to a process of refinement (the filling-in of implementation detail) before they can actually be implemented. The result of such a refinement process is an executable algorithm, which is either formulated in a programming language or in an executable subset of the specification language at hand. For example, Hartmann pipelines, when properly applied, may be considered a dataflow specification which is directly executable. Another example is the actor model, which has no specific application content and must be specialized to be executable.[citation needed]
An important use of specification languages is enabling the creation of proofs of program correctness (see theorem prover).[citation needed]
Media related to Specification languages at Wikimedia CommonsSource: Wikipedia. Article content is retrieved live through the MediaWiki API.
A specification language is a formal language in computer science used during systems analysis, requirements analysis, and systems design to describe a system at a much higher level than a programming language, which is used to produce the executable code for a system.
The Document Style Semantics and Specification Language (DSSSL) is an international standard developed to provide stylesheets for SGML documents. DSSSL consists of two parts: a tree transformation process that can be used to manipulate the tree structure of documents prior to presentation, and a formatting process that associates the elements in the source document with specific nodes in the target representation—the flow object tree. DSSSL specifications are device-independent pieces of information that can be interchanged between different platforms. DSSSL does not standardize the back-end formatters that generate the language's output. Such formatters may render the output for on-screen display, or write it to a computer file in a specific format (such as PostScript or Rich Text Format). Based on a subset of the Scheme programming language, it is specified by the standard ISO/IEC 10179:1996. It was developed by ISO/IEC JTC 1/SC 34 (ISO/IEC Joint Technical Committee 1, Subcommittee 34 - Document description and processing languages). SGML contains information in a machine-readable but not very human-readable format. A "stylesheet" is used to present the information stored in SGML in a more pleasing or accessible way. DSSSL can convert to a wide range of formats, including RTF, HTML, and LaTeX. DSSSL is compatible with any SGML-based document type, but it has been used most often with DocBook. In 1997, software engineer Geir Ove Grønmo published a syntax highlighting language definition for KEDIT. With the appearance of XML as an alternative to SGML, XML's associated stylesheet language XSL was also widely and rapidly adopted, from around 1999. Although DSSSL continued to be in use within the shrinking SGML field, XSL was very soon in use more extensively, and by more coders, than DSSSL had ever achieved. This was emphasised when previous SGML strongholds such as DocBook converted from SGML to XML, and also converted their favoured stylesheet language from DSSSL to XSL. Sometime in or before 1994, James Clark began drafting a "DSSSL Lite" specification for the consideration of the World Wide Web Consortium, since DSSSL was thought to be too complex for the World Wide Web.
Property Specification Language (PSL) is a temporal logic extending linear temporal logic with a range of operators for both ease of expression and enhancement of expressive power. PSL makes an extensive use of regular expressions and syntactic sugaring. It is widely used in the hardware design and verification industry, where formal verification tools (such as model checking) and/or logic simulation tools are used to prove or refute that a given PSL formula holds on a given design. PSL was initially developed by Accellera for specifying properties or assertions about hardware designs. Since September 2004 the standardization on the language has been done in IEEE 1850 working group. In September 2005, the IEEE 1850 Standard for Property Specification Language (PSL) was announced.
The Common Algebraic Specification Language (CASL) is a general-purpose specification language based on first-order logic with induction. Partial functions and subsorting are also supported.
Before the 1921 destruction of Tulsa’s Greenwood District, Black residents had created a remarkable center of business and community life. The district included stores, professional offices, entertainment venues and homes owned by Black citizens. Understanding Greenwood means learning what was built—not only what was burned.
MORE →Shirley Chisholm, elected in 1968.
