# Internal contextual grammar (Marcus) G = ({a,b}, { ab }, { (ab, (a, b)) }):
# the selector ab may be surrounded by the context (a, b):  ab -> a ab b.   L = { a^n b^n : n >= 1 }

# the words of the language: a string of terminal symbols (lower-case letters) that reaches component 1 is marked
[model.marks]
terminal = '\A[a-z]*\Z'

[axioms]
1 = ["ab"]

[rules]
# the selector ab is surrounded by the context (a, b)
ab -> a ab b
