What linguistics is all aboutWhat is a formal grammar?Contrary to the vague notion of common grammar, “formal grammars” are mathematically precise formalisms for systems of production rules.Usually one fixes an alphabet of symbols, one considers words as finite sequences of symbols, and formal languages are sets of words. A grammar is usually presented as a (recursive) set of production rules, allowing the derivation of words from other words. Formal languages are sets of words generated from some start symbol, using the grammar rules as production rules (rewrite rules, logic programming programs, etc). Grammar formalisms are stratified by their power of generation, or dually by the difficulty of their recognition (the inverse problem). The recognition problem is often described in terms of automata. One must be aware that this formal theory is completely abstract. Formal words may model words in the usual sense, but in general they will rather model sentences or discourse texts, in which case the corresponding formal language is a kind of ideal language defined by a corpus formally described as an infinite set of sentences. |