What is the most efficient way to convert spoken language dates to a normalized form?

Question

In spoken language processing, what is the best way to convert different ways of expressing date to a standard one that computer can understand? For example we can say many things like: Tomorrow, the day after tomorrow, two days later, next weekend, during this week, etc.

Answer 1

I have searched through the internet and found that I can do it with writing rules and patterns. The Olympus system is a complete dialog system that provides good ways of doing this through its dateTime binding filters.