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Blissymbols or Blissymbolics is a constructed language conceived as an ideographic writing system called Semantography consisting of several hundred basic symbols, each representing a concept, which can be composed together to generate new symbols that represent new concepts.
An unrestricted grammar is a formal grammar = (,,,), where . is a finite set of nonterminal symbols,; is a finite set of terminal symbols with and disjoint, [note 1]; is a finite set of production rules of the form , where and are strings of symbols in and is not the empty string, and
Naur changed two of Backus's symbols to commonly available characters. The ::= symbol was originally a :≡. The | symbol was originally the word "or" (with a bar over it). [9]: 14 BNF is very similar to canonical-form Boolean algebra equations that are, and were at the time, used in logic-circuit design. Backus was a mathematician and the ...
L-system trees form realistic models of natural patterns. An L-system or Lindenmayer system is a parallel rewriting system and a type of formal grammar.An L-system consists of an alphabet of symbols that can be used to make strings, a collection of production rules that expand each symbol into some larger string of symbols, an initial "axiom" string from which to begin construction, and a ...
where A, B, and C are nonterminal symbols, the letter a is a terminal symbol (a symbol that represents a constant value), S is the start symbol, and ε denotes the empty string. Also, neither B nor C may be the start symbol , and the third production rule can only appear if ε is in L ( G ), the language produced by the context-free grammar G .
The language generated by a grammar is the set of all strings of terminal symbols that can be derived, by repeated rule applications, from some particular nonterminal symbol ("start symbol"). Nonterminal symbols are used during the derivation process, but do not appear in its final result string.
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a sentential form is a member of () that can be derived in a finite number of steps from the start symbol ; that is, a sentential form is a member of {()}. A sentential form that contains no nonterminal symbols (i.e. is a member of Σ ∗ {\displaystyle \Sigma ^{*}} ) is called a sentence .