Exemplos de uso de Context-free em Inglês e suas traduções para o Português
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Context-free grammars specify programming language syntax.
So there exist context-sensitive languages which are not context-free.
These languages are not context-free, which can be shown using the pumping lemma.
We can represent grammars as finite state automata or context-free grammars.
Context-free languages are the theoretical basis for the syntax of most programming languages.
If the rule AB→ CD iseliminated from the above, then one obtains context-free languages.
Parser algorithms for context-free languages include the CYK algorithm and Earley's Algorithm.
This can be seen by taking the languages formula_27 and formula_28,which are both context-free.
Earley parsers are appealing because they can parse all context-free languages reasonably efficiently.
PCFGs extend context-free grammars similar to how hidden Markov models extend regular grammars.
Non-deterministic pushdown automata are another formalism equivalent to context-free grammars.
The language equality questiondo two given context-free grammars generate the same language?
If a language does not satisfy the condition given by the pumping lemma,we have established that it is not context-free.
Furthermore, it is undecidable whether a given context-free language is a linear context-free language.
To locate the regular languages in the Chomsky hierarchy,one notices that every regular language is context-free.
This expectation plays out in other ways, too,like when people perform context-free searches such as"is it going to rain today?
This set is context-free, since the union of two context-free languages is always context-free.
This makes it one of the most efficient algorithms for recognizing general context-free languages in practice.
Formally, the set of all context-free languages is identical to the set of languages accepted by pushdown automata PDA.
Another example of a context-sensitive language that is not context-free is"L"{"ap":"p" is a prime number.
Deterministic context-free languages is a subset of context-free languages that can be recognized in linear time.
The languages generated by these formalisms properly lie between the context-free and context-sensitive languages.
However, the intersection of a context-free language and a"regular" language is context-free, and the variant of the problem where"B" is a regular grammar is decidable.
In classical formal language theory,the theorem can be used to prove that certain context-free languages are inherently ambiguous.
The best known algorithm to test membership in any context-free language is Valiant's algorithm, taking O(n2.378) time, where n is the length of the string.
By the Chomsky-Schützenberger theorem, one can conclude that L G{\displaystyle L_{G}}does not admit an unambiguous context-free grammar.
In formal language theory,deterministic context-free languages(DCFL) are a proper subset of context-free languages.
To locate the regular languages in the Chomsky hierarchy,one notices that every regular language is context-free.
E"=== Semantics===The fundamental difference between context-free grammars and parsing expression grammars is that the PEG's choice operator is"ordered.
In Chomsky's generative grammar framework,the syntax of natural language was described by context-free rules combined with transformation rules.