Problem 2.2: [Homework: Due Weds, 31 January, 12:45] When processing a stream of symbols such as the stream of ascii symbols in source code, there is a need to recognize tokens. These are substrings, special sequences of symbols such as while. The stream of symbols in the source code for example needs to be recognized as a stream of tokens. This task is known as lexical analysis. Lexical analysis is a task that basic finite state machines can perform. The NFA below recognizes - synonymously, accepts only the three strings over the alphabet (a, b, c]: ac, ab and bc. The states are named by the numbers 0, 1, 2, 3, 4, 5, 6 0 2 Use the given NFA to obtain an NFA that accepts all and only those strings over the alphabet [a, b, c, d) that contain as substrings the strings ac, ab and bc. So cbadc would not be accepted, but cbacd would be accepted because ac is not a substring of cbadc but is a substring of cbacd Apply the subset construction to obtain a DFA from your NFA Next, use your DFA to obtain a DFA that accepts all and only those strings over the alphabet a, b, c, d) that do not contain as substrings any of the strings ac, ab and bc