Search results
Results From The WOW.Com Content Network
In formal language theory, a context-free grammar is in Greibach normal form (GNF) if the right-hand sides of all production rules start with a terminal symbol, optionally followed by some variables. A non-strict form allows one exception to this format restriction for allowing the empty word (epsilon, ε) to be a member of the described language.
To convert a grammar to Chomsky normal form, a sequence of simple transformations is applied in a certain order; this is described in most textbooks on automata theory. [4]: 87–94 [5] [6] [7] The presentation here follows Hopcroft, Ullman (1979), but is adapted to use the transformation names from Lange, Leiß (2009).
In computer science, Backus–Naur form (BNF; / ˌ b æ k ə s ˈ n aʊər /; Backus normal form) is a notation used to describe the syntax of programming languages or other formal languages. It was developed by John Backus and Peter Naur. BNF can be described as a metasyntax notation for context-free grammars. Backus–Naur form is applied ...
Context-free parsing for Chomsky normal form grammars was shown by Leslie G. Valiant to be reducible to Boolean matrix multiplication, thus inheriting its complexity upper bound of O(n 2.3728639). [ 16 ] [ 17 ] [ b ] Conversely, Lillian Lee has shown O ( n 3−ε ) Boolean matrix multiplication to be reducible to O ( n 3−3ε ) CFG parsing ...
In boolean logic, a disjunctive normal form (DNF) is a canonical normal form of a logical formula consisting of a disjunction of conjunctions; it can also be described as an OR of ANDs, a sum of products, or — in philosophical logic — a cluster concept. [1] As a normal form, it is useful in automated theorem proving.
Botola, or GNF 1, Moroccan football league division 1; Botola 2, ... Greibach normal form; Guinean franc, the currency of Guinea This page was last edited on ...
The sixth normal form is currently as of 2009 being used in some data warehouses where the benefits outweigh the drawbacks, [9] for example using anchor modeling.Although using 6NF leads to an explosion of tables, modern databases can prune the tables from select queries (using a process called 'table elimination' - so that a query can be solved without even reading some of the tables that the ...
In Boolean logic, a formula is in conjunctive normal form (CNF) or clausal normal form if it is a conjunction of one or more clauses, where a clause is a disjunction of literals; otherwise put, it is a product of sums or an AND of ORs.