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Every terminal/nonterminal needs to be in a seperate input field. (for both the grammar and the word).
There is no

so A > A B  a
for example is entered as A > A B
and A > a
.Which symbols are terminal, and which nonterminal, is automaticaly deduced from which symbols are present on the lefthandside.
1
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Rules are of the form
lhs → rhs
(you can use >
or →
).Righthandsides can have multiple options seperated with

.ɛ
may also be written as epsilon
or EPSILON
.Terminals in a word need to be seperated by spaces.
Here are some example grammars:
if_expr → IF bool THEN bool if_tail
if_tail → ELIF bool THEN bool  ELSE bool  ɛ
bool → TRUE  FALSE
S > A B  +
A > A A  0
B > 1  2  S S
Input