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Shallow semantic parsing is concerned with identifying entities in an utterance and labelling them with the roles they play. Shallow semantic parsing is sometimes known as slot-filling or frame semantic parsing, since its theoretical basis comes from frame semantics, wherein a word evokes a frame of related concepts and roles.
Some parser generators, such as the byacc-derived BtYacc ("Backtracking Yacc"), give the generated parser the ability to try multiple attempts to parse the tokens. In the problem described here, if an attempt fails because of semantic information about the identifier, it can backtrack and attempt other rules.
Semantic analysis or context sensitive analysis is a process in compiler construction, usually after parsing, to gather necessary semantic information from the source code. [1] It usually includes type checking , or makes sure a variable is declared before use which is impossible to describe in the extended Backus–Naur form and thus not ...
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.
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 .
Part-of-speech tagging (which resolves some semantic ambiguity) is a related problem, and often a prerequisite for or a subproblem of syntactic parsing. Syntactic parses can be used for information extraction (e.g. event parsing, semantic role labelling, entity labelling) and may be further used to extract formal semantic representations.
Another chart parsing algorithm is the Cocke-Younger-Kasami (CYK) algorithm. Chart parsers can also be used for parsing computer languages. Earley parsers in particular have been used in compiler-compilers where their ability to parse using arbitrary Context-free grammars eases the task of writing the grammar for a particular language.
The following example demonstrates the common case of parsing a computer language with two levels of grammar: lexical and syntactic. The first stage is the token generation, or lexical analysis , by which the input character stream is split into meaningful symbols defined by a grammar of regular expressions .