Another interesting question is: how many possible successful matches are there for a given input string. For example: How many ways can (a?){m}(a*){m} match t

Another interesting question is: how many possible successful matches are there for a given input string. For example: How many ways can (a?){m}(a*){m} match the string a{m} i.e. input m repetitions of the letter 'a'. https://github.com/mike-french/myrex#ambiguous-example https://github.com/mike-french/myrex#ambiguous-example The answer is a dot product of two vectors sliced from Pascal's Triangle. For m=9, there are 864,146 successful matches.