%% g2.pl

%% This is a context-free grammar for strings of balanced parentheses where
%% the symbol 'o' represents the open parenthesis '(' and
%% the symbol 'c' represents the closed parenthesis ')'.

%% The grammar is:
%% s -> lambda | o s c s

variable(s).

terminal(o).
terminal(c).

rule(s, []).
rule(s, [o, s, c, s]).