GRAMMAR CHECKING

Detection and correction of grammatical errors by taking into account adjacent words in the sentence or even the whole sentence are much more difficult tasks for computational linguists and software developers than just checking orthography.

Grammar errors are those violating, for example, the syntactic laws or the laws related to the structure of a sentence. In Spanish, one of these laws is the agreement between a noun and an adjective in gender and grammatical number. For example, in the combination *mujer viejos each word by itself does exist in Spanish, but together they form a syntactically ill-formed combination. Another example of a syntactic agreement is the agreement between the noun in the role of subject and the main verb, in number and person (*tú tiene).

The words that must agree can be located in quite different parts of the sentence. For example, it is rather difficult for a program to find the error in the following sentence: *Las mesas de madera son muy largos.

Other types of grammatical errors include incorrect usage of prepositions, like in the phrases *debajo la puerta, or *¡basta con verla!, or *casarse a María. Some types of syntactic errors may be not so evident even for a native speaker.

It became clear long ago that only a complete syntactic analysis (parsing) of a text could provide an acceptable solution of this task. Because of the difficulty of such parsing, commercial grammar checkers are still rather primitive and rarely give the user useful assistance in the preparation of a text. The Windows Sources, one of the well-known computer journals, noted, in May 1995, that the grammar checker Grammatik in the WordPerfect text editor, perhaps the best grammar checker in the world at that time, was so imperfect and disorienting, that “nobody needs a program that’s wrong in more cases than it’s right.”

In the last few years, significant improvements have been made in grammar checkers. For example, the grammar checker included in Microsoft Word is helpful but still very far from perfection.

Sometimes, rather simple operations can give helpful results by detecting some very frequent errors. The following two classes of errors specific for Spanish language can be mentioned here:

· Absence of agreement between an article and the succeeding noun, in number and gender, like in *la gatos. Such errors are easily detectable within a very narrow context, i.e., of two adjacent words. For this task, it is necessary to resort to the grammatical categories for Spanish words.

· Omission of the written accent in such nouns as *articulo, *genero, *termino. Such errors cannot be detected by a usual spell checker taking the words out of context, since they convert one existing word to another existent one, namely, to a personal form of a verb. It is rather easy to define some properties of immediate contexts for nouns that never occur with the corresponding verbs, e.g., the presence of agreed articles, adjectives, or pronouns [38].

We can see, however, that such simplistic techniques fail in too many cases. For example, in combinations such as *las pruebas de evaluación numerosos, the disagreement between pruebas and numerosos cannot be detected by considering only the nearest context.

What is worse, a program based on such a simplistic approach would too frequently give false alarms where there is no error in fact. For example, in the correct combination las pruebas de evaluación numerosas, such a simplistic program would mention disagreement in number between the wordforms evaluaciónand numerosas.

In any case, since the author of the text is the only person that definitely knows what he or she meant to write, the final decision must always be left up to the user, whether to make a correction suggested by the grammar checker or to leave the text as it was.

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<== попередня сторінка	\|	наступна сторінка ==>
SPELL CHECKING	\|	STYLE CHECKING

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