Today I covered some resources that can be used to improve the use cases that you submit for Homework 4. First, the class website for the 2005 version of this class had a page pointing to use case examples from Alastair Cockburn's Writing Effective Use Cases book. On that page, take a look at the examples associated with slide 14 and slide 15. In particular, pay attention to how those examples make use of what they call "Alternatives" and they way they can associate multiple problems with a single action step. The other resource I pointed to was Lecture 7 from the Fall 2008 version of this class. In that lecture, there is a section that discusses "style guidelines" for writing use cases (slides 21 to 34), again taken from Cockburn's excellent book. I hope these two resources are useful for helping you to understand use cases a bit better and to write high-quality use cases for Homework 4.