Editing Grammar checker (section)

==Technical issues==
The earliest writing style programs checked for wordy, [[wikt:trite|trite]], [[cliché]]d, or misused phrases in a text. This process was based on simple [[pattern matching]]. The heart of the program was a list of many hundreds or thousands of phrases that are considered poor writing by many experts. The list of questionable phrases included alternative wording for each phrase. The checking program would simply break text into sentences, check for any matches in the phrase dictionary, flag suspect phrases and show an alternative. These programs could also perform some mechanical checks. For example, they would typically flag doubled words, doubled punctuation, some [[capitalization]] errors, and other simple mechanical mistakes.

True grammar checking is more complex. While a [[programming language]] has a very specific syntax and grammar, this is not so for [[natural language]]s. One can write a somewhat complete [[formal grammar]] for a natural language, but there are usually so many exceptions in real usage that a formal grammar is of minimal help in writing a grammar checker. One of the most important parts of a natural language grammar checker is a [[dictionary]] of all the words in the language, along with the part of speech of each word. The fact that a natural word may be used as any one of several parts of speech (such as "free" being used as an adjective, adverb, noun, or verb) greatly increases the complexity of any grammar checker.

A grammar checker will find each sentence in a text, look up each word in the dictionary, and then attempt to [[Parsing|parse]] the sentence into a form that matches a grammar. Using various rules, the program can then detect various errors, such as agreement in [[Grammatical tense|tense]], number, [[word order]], and so on. It is also possible to detect some stylistic problems with the text. For example, some popular style guides such as [[The Elements of Style]] deprecate excessive use of the [[passive voice]]. Grammar checkers may attempt to identify passive sentences and suggest an active-voice alternative.

The software elements required for grammar checking are closely related to some of the development issues that need to be addressed for [[speech recognition]] software. In voice recognition, parsing can be used to help predict which word is most likely intended, based on part of speech and position in the sentence. In grammar checking, the parsing is used to detect words that fail to follow accepted grammar usage.

Recently,{{when|date=May 2019}} research has focused on developing algorithms which can recognize grammar errors based on the [[context (language use)|context]] of the surrounding words.{{clarify|date=May 2019}}<!-- Isn't that...every grammar checker?-->