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Semantic parsing is the task of converting a natural language utterance to a logical form: a machine-understandable representation of its meaning. [1] Semantic parsing can thus be understood as extracting the precise meaning of an utterance.
With the hack in the above example, when the lexer finds the identifier A it should be able to classify the token as a type identifier. The rules of the language would be clarified by specifying that typecasts require a type identifier and the ambiguity disappears. The problem also exists in C++ and parsers can use the same hack. [1]
These examples all only require lexical context, and while they complicate a lexer somewhat, they are invisible to the parser and later phases. A more complex example is the lexer hack in C, where the token class of a sequence of characters cannot be determined until the semantic analysis phase since typedef names and variable names are ...
A classic example of a problem which a regular grammar cannot handle is the question of whether a given string contains correctly nested parentheses. (This is typically handled by a Chomsky Type 2 grammar, also termed a context-free grammar .)
Parsing, syntax analysis, or syntactic analysis is a process of analyzing a string of symbols, either in natural language, computer languages or data structures, conforming to the rules of a formal grammar by breaking it into parts. The term parsing comes from Latin pars (orationis), meaning part (of speech). [1]
More formally, a syntactic predicate is a form of production intersection, used in parser specifications or in formal grammars. In this sense, the term predicate has the meaning of a mathematical indicator function. If p 1 and p 2, are production rules, the language generated by both p 1 and p 2 is their set intersection.
For example, denotational semantics of functional languages often translate the language into domain theory. Denotational semantic descriptions can also serve as compositional translations from a programming language into the denotational metalanguage and used as a basis for designing compilers .
Computational semantics is the study of how to automate the process of constructing and reasoning with meaning representations of natural language expressions. [1] It consequently plays an important role in natural-language processing and computational linguistics .