Question 13
Replacement rules describe how to rewrite a letter as a string of letters. For example, A→BB and B→ABA replace each A by BB and each B by ABA. Starting with A, these rules give A→BB→ABAABA→BBABABBBBABABB in three steps. At every step, all letters are replaced according to the rules.
Which rule set can produce BAACCACCABAB?
Editorial interpretation: the new target question does not fix an initial letter; it asks whether these rules can produce the target.
Which rule set can produce BAACCACCABAB?
Editorial interpretation: the new target question does not fix an initial letter; it asks whether these rules can produce the target.