# Insertion-deletion system (V, T, A, I, D) with V = T = {a,b}, A = { ab },
# I = { (a, ab, b) } (insert ab between a and b), D = {}.   L = { a^n b^n : n >= 1 }
# ins(u,y,v): insert y where u ends right before it and v starts right after it.

# 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]
# insert "ab" between an a and a b
ins(a, ab, b)
