Hmmm? you ask. What's the man mumbling about this time. Well, shortest path is both a theoretical problem class in computer science, but it's also a good model to use in measuring mobile phone usability.
Imagine you've just taken a wonderful picture of a evening, the sky just before sunset. Your 5 megapixel camera takes accurate images. Why did you take the photo? Well, you can use it as a background image in the phone. You can also download (or, let's just say send) it to your computer back home. Or you can send it to a social network, photo gallery, or as an email attachment.
The crucial question is:
how, when, does it work? Does it reach the audience? Are you happy?
Simple as that.
How do you do it?