booleanGrammar          A constant function which returns the BNF
                        (Backus-Naur Form) of a context-free grammar
                        for the XOR problem.
compileBNF              Compile a BNF (Backus-Naur Form) of a
                        context-free grammar.
compileShortPT          Produces a production table with non-recursive
                        productions only.
derive                  Derives the identifier list which expands the
                        non-terminal identifier.
id2symb                 Convert a numeric identifier to a symbol.
isNonTerminal           Is the numeric identifier a non-terminal
                        symbol?
isTerminal              Is the numeric identifier a terminal symbol?
makeProductionTable     Produces a production table.
makeRule                Transforms a single BNF rule into a production
                        table.
makeStartSymbol         Extracts the numerical identifier of the start
                        symbol of the grammar.
makeSymbolTable         Build a symbol table from a character string
                        which contains a BNF.
newBNF                  Convert grammar file into a constant function.
readBNF                 Read text file.
rules                   Returns all indices of rules applicable for a
                        non-terminal identifier.
symb2id                 Convert a symbol to a numeric identifier.
writeBNF                Write BNF into text file.
xegaBNF                 Package xegaBNF
