Abstract: A method, device and computer program product for parsing linguistic input data by a computer system, in accordance with a grammar of a Formalized Natural Language. The grammar of the Formalized Natural language is a text grammar representing an infinite set of texts of type Text and is stored in electronic form in a computer readable medium constituting a text grammar device. This text grammar is defined by a set of four elements W, N, R and Text. W is a finite set of invariable words of type Word, to be used as terminal, elementary expressions of a text. N is a finite set of non-terminal help symbols, to be used for the derivation and the representation of texts. R is a finite set of inductive rules for the production of grammatical expressions of the Formalized Natural Language, and Text is an element of N and start-symbol for grammatical derivation of all texts of type Text of the Formalized Natural Language.