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Context-free grammar

Context-free grammar
V → w where V is a single nonterminal symbol, and w is a string of terminals and/or nonterminals (w can be empty). A formal grammar is considered "context free" when its production rules can be applied regardless of the context of a nonterminal. No matter which symbols surround it, the single nonterminal on the left hand side can always be replaced by the right hand side. Context-free grammars arise in linguistics where they are used to describe the structure of sentences and words in natural language, and they were in fact invented by the Linguist Noam Chomsky for this purpose, but have not really lived up to their original expectation. By contrast, in computer science, as the use of recursively defined concepts increased, they were used more and more. In linguistics, some authors use the term phrase structure grammar to refer to context-free grammars, whereby phrase structure grammars are distinct from dependency grammars. Background[edit] can be logically parenthesized as follows: where

Related:  CFDG: Context Free Design Grammarlanguages

Kontextfreie Sprache In der Theoretischen Informatik ist eine kontextfreie Sprache (englisch context-free language, CFL) eine formale Sprache, die durch eine kontextfreie Grammatik beschrieben werden kann. Eine kontextfreie Grammatik erlaubt einen definierten Leseprozess (Interpretation) von Ausdrücken einer formalen Sprache. Dabei kann zum einen entschieden werden, ob ein Ausdruck den Regeln der Grammatik entspricht, und zum anderen im Verlauf der Analyse ein Syntaxbaum erstellt werden. Ein Programm, das dies leistet, heißt Parser. Parser werden insbesondere zur Verarbeitung von Programmiersprachen verwendet.

Regular language In theoretical computer science and formal language theory, a regular language is a formal language that can be expressed using a regular expression. (Note that the "regular expression" features provided with many programming languages are augmented with features that make them capable of recognizing languages that can not be expressed by the formal regular expressions (as formally defined below).) Alternatively, a regular language can be defined as a language recognized by a finite automaton. Context-free language In formal language theory, a context-free language (CFL) is a language generated by some context-free grammar (CFG). Different CF grammars can generate the same CF language, or conversely, a given CF language can be generated by different CF grammars. It is important to distinguish properties of the language (intrinsic properties) from properties of a particular grammar (extrinsic properties). The set of all context-free languages is identical to the set of languages accepted by pushdown automata, which makes these languages amenable to parsing. Indeed, given a CFG, there is a direct way to produce a pushdown automaton for the grammar (and corresponding language), though going the other way (producing a grammar given an automaton) is not as direct.

Fortran Fortran (previously FORTRAN, derived from Formula Translating System) is a general-purpose, imperative programming language that is especially suited to numeric computation and scientific computing. Originally developed by IBM in New York City[1] in the 1950s for scientific and engineering applications, Fortran came to dominate this area of programming early on and has been in continuous use for over half a century in computationally intensive areas such as numerical weather prediction, finite element analysis, computational fluid dynamics, computational physics and computational chemistry. It is one of the most popular languages in the area of high-performance computing[2] and is the language used for programs that benchmark and rank the world's fastest supercomputers. Fortran encompasses a lineage of versions, each of which evolved to add extensions to the language while usually retaining compatibility with previous versions. Capitalization[edit]

Background directive - Context Free Art From Context Free Art The shapes rendered by Context Free/CFDG are drawn on a canvas that starts out with a background color. The default color is opaque white, but this can be changed using a background directive. A background directive is a line in the CFDG file that starts with the word 'background' that is followed by set of color adjustments in curly braces. The adjustments are relative to the default background color of opaque white (hue = 0, saturation = 0, brightness = 1, alpha = 1). If there are more than one background directive then only the first is used.

Speedcoding Speedcoding or Speedcode was the first higher-level language created for an IBM computer.[1] The language was developed by John Backus in 1953 for the IBM 701 to support computation with floating point numbers.[2] The idea arose from the difficulty of programming the IBM SSEC machine when Backus was hired to calculate astronomical positions in early 1950.[3] The speedcoding system was an interpreter and focused on ease of use at the expense of system resources. It provided pseudo-instructions for common mathematical functions: logarithms, exponentiation, and trigonometric operations.

Context Free Art – Tutorial 1 » Magic & Love Interactive After we can create different primitive shapes, we start to combine them together. We cannot simply put all the primitive shapes within one single shape rule, like: startshape MyShape rule MyShape { CIRCLE {} TRIANGLE {} SQUARE {} } Multiple shapes A Brief, Incomplete, and Mostly Wrong History of Programming Languages 1801 - Joseph Marie Jacquard uses punch cards to instruct a loom to weave "hello, world" into a tapestry. Redditers of the time are not impressed due to the lack of tail call recursion, concurrency, or proper capitalization. 1842 - Ada Lovelace writes the first program. She is hampered in her efforts by the minor inconvenience that she doesn't have any actual computers to run her code. Enterprise architects will later relearn her techniques in order to program in UML. 1936 - Alan Turing invents every programming language that will ever be but is shanghaied by British Intelligence to be 007 before he can patent them.

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