Expressions Date expressions can be given a good description using FSAs. - Sketch an FSA for 'full dates' as in monday the first of january tuesday the twenty first of february where you have a day of the week, followed by a number word, followed by the name of a month. To simplify things, use lower case through out. Don't worry about month-number dependencies, such as the fact that September has 30 days, but October has 31 . Stop once it handles a couple of days of the week, a couple of months, and a few 1 word and 2 word numbers. - then think how you might adapt it so that - you do not need to necessarily have a day of the week expression at the beginning (the first of april is ok) - you do not necessarily need to have a month expression at the end (monday the first and the the first are ok) - you could stop immediately after giving a day of the week (monday is ok) Its worth recalling for this that an FSA could have more than one start state