review of Week 10

The annoying assignments, exercises, quizzes and term tests seem to be paused except for CSC236. This weekend i have to engage into the second last assignment with my partner. I also have a somehow big project of csc207 to worry about. Insipte of the workload of a computer science student, i now write for my 6%~11% of the final mark.
These two week we saw pretty much things about finite state automata and regular expressions. Regular expression is a descriptive way to express the language. We can design our own language with different alphabet using regular expressions. Through the example in the lecture, such as an alphabet of binary numbers containing even or odd zeros, i learned a logical procedure to analyze the syntax between various languages. The interesting part for me is the algebra on regexes. Without changing the language, one can apply some principles such as: commutativity, distributivity to the regular expressions. This simplifying process allows more variations on a language and it provides some interesting design patterns of a language.
Another thing is the DFA, or DFSA. The first time i saw it was in CSC148 when we were doing the graph algorithm. It seems there is quite a few connection from the DFA to graph algorithm. Machines of DFA accept their unique pattern of strings. We can easily find out whether a string is valid to the machine by traversing between the states. The hard part is how we construct a desired machine for a particular collection of strings. By observing the pattern of some strings, we need to derive some crucial parts of the machine like the state invariants and the transition functions. A graph is usually helpful to verify the state the next character heads is correct, which is to say, we need to carefully set our initial state, final state, states between and all the edges. Such things is really thoughtful.