1. Write a regular expression that captures the set of strings composed of a, b, and c, 'd', where any string uses at most two of the three letters (for example,abbab is a valid string, or bccbb, or ccacaa, but not abccba; strings that contain only one of the three letters are also fine). 2. Give a non-deterministic finite automaton that captures the regular expression from above. Show the automaton in graphical form. 3. Using the construction described in class, give a deterministic version of the automaton. You only need to show the transition table.

2. Give a non-deterministic finite automaton that captures the regular expression from above. Show the automaton in graphical form.

3. Using the construction described in class, give a deterministic version of the automaton. You only need to show the transition table.